what causes a hydraulic pump to get hot pricelist

Is your hydraulic pump getting excessively hot during normal operation? Pumps do generate heat when running, however they are designed with specific heat parameters in mind. Overheating is an abnormal condition that leads to destructive issues such as thinning of hydraulic fluid, which leads to reduced lubrication, metal-on-metal contact of moving parts. And accelerated pump wear and failure.

Therefore it is never a good idea to ignore a pump that is exceeding its heat parameters under normal load. There are a number of factors that contribute to an excess buildup of heat and in this article, we’ll explain some of these issues.

Hydraulic fluid viscosity refers to the thickness or “resistance to pouring” of your hydraulic fluid. This is very important to the correct operation of your pump. The fluid not only transmits the power that moves your drives and actuators. It also lubricates internal components and removes heat from the system. Hydraulic fluid is designed to operate at a specific temperature range. As it heats, it becomes thinner and eventually it will lose the ability to lubricate moving parts. The increased friction may cause the pump to heat up, and naturally increased wear will be taking place when this is happening. On the other hand, hydraulic fluid that is too thick flows less efficiently within the system, which also results in heat buildup.

Fluid that is contaminated with dirt, debris, water and other impurities may cause heat build up in a few ways. Blocked fluid filters, pipes and strainers place undue load on the pump or even lead to pressure drops on the back side of filters that cause cavitation.

Low fluid levels can result in a condition in which not enough flow is reaching the critical hydraulic components and moving parts. This is known as oil starvation and just like running your car without oil, it will increase metal-on-metal friction and lead to increased heat and wear. Oil starvation can also be caused by clogged hydraulic filters, incorrect fluid reservoir design.

Cavitation is the rapid formation and implosion of air cavities in the hydraulic fluid. When these air cavities collapse under pressure, they generate a lot of heat. In fact, temperatures can reach up to 2700 degrees C at the point of implosion! Not only does cavitation compromise the lubrication properties of the oil, the excessive heat that is generated is extremely damaging to the hydraulic pump and the system as a whole. Attacking hoses and seals and causing metal components to expand and wear.

This happens when air makes its way into the system via air leaks at points like pump seals, and pipe fittings. And what happens next in a hydraulic system? Compression! Air generates heat when compressed, which naturally leads to an increase in temperature if left untreated. In extreme circumstances it can also lead to ‘hydraulic dieseling’ whereby compressed air bubbles actually explode in the same process that powers diesel engines. This is not good and leads to degradation of the fluid and damage to system components through loss of lubrication and burning of seals.

As pumps wear, the internal leakage or “slippage” increases. Essentially, fluid is able to make its way past tight fitting components, which reduces the efficiency of the pump, but in addition, as this occurs, fluid moves from a high pressure to a low pressure without doing any mechanical work, since according to the laws of physics energy cannot be destroyed, it is instead converted into heat.

A build-up of excessive heat is a symptom of hydraulic pump problems, but it is far from the only signal that there may be something wrong. There are other important warning signs that you should pay attention to. These include unusual noises, pressure problems and flow problems. Each of these symptoms provide clues about any potential pump problems that need to be addressed - so it’s important to familiarise yourself with all of these issues. To help, we’ve created a downloadable troubleshooting guide containing more information about each of these issues. So that you can keep your system up and running and avoid unplanned downtime. Download ithere.

Hydraulic pumps generate heat while they run. However, hydraulic fluid temperature should never exceed180 degreesF (82 degrees C) under normal working conditions. If your hydraulic pump temperature rises above this, then that is a sign that your pump is likely overheating. One of the most common causes of hydraulic system failure is a hydraulic pump that runs too hot or overheats.

When a hydraulic pump runs at a too-high temperature for too long, it can ultimately lead to pump failure. Once a hydraulic pump begins to fail, it can potentially damage the entire hydraulic system by sending contaminants and debris into the system that can damage its other components.

In addition, when some hydraulic fluids are subject to high temperatures, they can thin and lose their viscosity. When hydraulic fluid is too thin, it is much more likely to leak, and fluid that has lost its viscosity cannot lubricate your pump properly. Extremely hot fluid can also damage pump seals, further increasing the chance of a pump leak.

Some hydraulic fluids thicken and oxidize when exposed to high heat instead of thinning. When hydraulic fluids are too thick, they can restrict flow throughout the entire hydraulic system, which leads to your system heating up even further.

The sooner you determine why your hydraulic pump is running hot and repair the cause of the problem, the less likely your hydraulic system will develop irreversible damage or fail completely.

Hydraulic pumps overheat for many reasons. Just a few of the most common causes of hydraulic pump overheating include: Contaminated hydraulic fluid. When fluid has debris and dirt, contaminant particles can quickly build up on hydraulic system filters, leading to filter clogs. Your pump has to work harder to pump fluid through clogged filters, which leads to overheating.

Aeration. Air leaks at seals and fittings on your hydraulic system components can lead to air entering your system and forming bubbles in your fluid. Air bubbles generate heat when your system compresses them and then pass this heat into the surrounding fluid, overheating it.

Low reservoir fluid. Since your hydraulic system releases some of the heat it creates into reservoir fluid, a low reservoir fluid level can contribute to overheating.

Blocked or damaged heat exchanger. This component is also an important part of your hydraulic pump"s cooling system. If it is blocked or damaged, then it cannot help remove heat from your pump properly.

Once your hydraulic pump beings overheating, you need to find the cause of the problem and repair it. That way, your pump can begin operating within its ideal temperature range again.

If your pump overheats due to fluid contamination, then either remove all contaminants from existing fluid or remove the current contaminated fluid from the system and add fresh fluid. Be sure to filter all fresh hydraulic fluid before you add it to your system because even this fresh fluid can contain contaminants. Also, replace your fluid filters on a regular basis to prevent the overheating that can occur when these filters become blocked with debris.

If air has entered your system through leaky seals and fittings, then have a hydraulic system repair expert inspect and replace or tighten these fittings. Have a hydraulic system repair expert also look at heat exchanger damage to determine if the exchanger needs repairing or replacing.

Finally, be sure to check your system"s reservoir fluid level on a regular basis. Add new fluid when necessary to help this reservoir perform its important task of helping to keep your pump cool.

Your hydraulic pump should always operate within its ideal temperature range. If your pump is running hot, then contact the hydraulic pump experts at Quad Fluid Dynamics, Inc., forhydraulic pump diagnosis and repairtoday.

Overheating isa frequent problemwithin hydraulic systems that may be determined by specific components. Thisinternal problem lies within the pump and causes a hydraulic system to overheat in the following ways:

Contaminated hydraulic fluid is a common cause for a Hydraulic system to overheat. This can occur when the container is not sealed properly which causes dust, dirt,debris,or moisture to contaminate the fluid.With hydraulic systems running at higher pressures and more efficiently than ever before, it is important tomonitorthe cleanliness of one’s hydraulic fluid. Reducing contamination can decrease damage andwillallowoneto get the most out oftheirequipment.

Wrong valve calibration could resultin pressure difficulties which can cause a hydraulic system to overheat. The main cause of this is when a facility’s plant design changes and maintenance recalibrate the pressure relief valves for the updated operating pressure. If maintenance adjusts the pressure,and it stilldoes notsolve the problem, the pressure relief valve may have to be replaced entirely. Erosion to a valve is a common occurrence as dirt and debris settle and collectthroughout time. Maintaining the correct pressure will help your system keep up with production and not slow down.

Aeration in a hydraulic system can bea common issueand is caused by an outside air leak in the suction line.The pressure used in the suction line of hydraulic systems is below atmospheric pressure, so oilcannotleak out, but air can leak in.This will occur when there are loose, leaky seals and fittings which will allowtheair to seep in.Aeration can have severalnegative effectson top of overheatingsuch as increasedpump cavitation, excessive noise, and loss of horsepower.Some symptoms of Aeration may include foaming of the fluid, irregular movements, and banging and or loud clicking noises as the hydraulic system compresses and decompresses.

A blocked heat exchanger is significant toheating one’s hydraulic system, while cooling it down is just as important.Aninfrared thermometer isan effective wayto checkthe temperatureof a heat exchanger. Theadjustments can be made according tothedesign of theflow rateof oil.Make sure to replace the fluid fitterslocatedin the pumpon a regular basis to ensure theywill not get blocked andoverheat.

Oil Type plays a critical role inany hydraulic system. The wrong oil will not only affect the performance of the system but also cut down the lifespan of the machine. Theoil Viscositydeterminesthe maximum and minimum temperatures in which a hydraulic system can safelyoperate.Thin oils have a lowviscosity andflow more easily at low temperaturesthanthicker oils that have a higherviscosity.If the oil is too thin it can cause internal friction whichcreates heat and cancausethe system to overheat.

Low reservoir fluid is a common cause ofoverheating in hydraulic systems as itreleasesbuilt-upheatfrom the machineintothe fluid. Not having enough reservoir fluid cancontribute tocavitation andultimate damage to the pump.

Hydraulic pump failure candamage the entire hydraulic system.When a pump fails,debris, dirt, and grime kick out downstreamand can affect theoil,filter,valves, fluid, and actuator.Contactour KICK@$$ hydraulic system repair professionalsat Allied Hydraulic to avoid these problems.

You can use multiple different upgrades and tuning methods on hydraulic systems. Many users will invest in upgrades that promise more flow and speed. The issue with these upgrades is that they"re not always fit for the hydraulic systems they"re applied to.

Since everything needs to stay in balance, you must make sure your upgrades match the entirety of your hydraulic system. For example, a higher flow pump can help give increased capabilities to a hydraulic system, but did you also check to see if the system"s hoses and piping can handle that increase in flow?

The increased flow can hit your smaller hoses hard and require more pressure just to get through them. This goes for any part of the hydraulic system that isn"t readily capable of handling more flow.

If a component becomes a flow throttle, the increase in pressure at the site can cause an overall pressure drop in the system. Also, the energy required to force flow will directly translate to an increase in heat, which lowers the systems efficiency and effectiveness.

When you make upgrades, also ascertain if you need to change other components. In the example of the higher flow pump, you can simply increase your hose size, and that makes all the difference.

When hydraulic oil is getting overheated, there could be several common causes that also cause the system to overheat. First, it is crucial to understand the type of hydraulic system you are using to begin troubleshooting why the system is overheating.

The first cause of hydraulic oil overheating is when the hydraulic equipment system parts and components are nearing the end of their useful lifespans. As they degrade, due to increased internal leakage, they have to work harder to maintain the desired system pressure.

For example, your hydraulic pump is wearing out and needs to be replaced. Due to internal wear pressurised fluid escapes from the high pressure side to the low pressure side generating heat increasing the temperature of the hydraulic fluid and causing circuit overheating.

It is understood that you may want to make system upgrades or changes to customize the system to reflect your specific needs. However, when you do not consider the entire system, it can cause the system to work hard, give off more heat, and increase hydraulic oil temperatures, leading to circuit overheating.

For instance, you may want to increase the fluid flow rate through the system. However, you did not account for the size of hoses and tubing to accommodate the higher flow rates. As a result, the system has to work hard to force the increased flow rates through incompatible hoses and tubes, resulting in more heat generation and fluid overheating.

Tweaking your hydraulic system is perfectly acceptable to optimize its performance. However, where many people go wrong is they only adjust one part of the system and fail to think about how the adjustment will impact other parts of the system.

For example, suppose you make an adjustment to the pump compensator and increase the pressure yet fail to also make a similar adjustment to the relief valve. In this instance the relief valve will blow off more frequently generating more heat and therefore increasing the circuit fluid temperature.

Every component in a hydraulic system imposes a load on the pump, this is referred to as the pressure drop across the particular component. The figure will vary depending upon the flow rate and the energy lost from the fluid due to the pressure drop is converted into heat. If the overall pressure drop across all the components in the circuit unexpectedly increases so the heat generated across the circuit will also increase.

If the fluid is not cooled to compensate for this the fluid temperature continues to increase as the other parts and components generate excessive heat.

If there is dirt, sludge, debris, or water in the hydraulic fluid, the system will generate more heat as it attempts to compensate for the contaminants and push the fluid through the system. Therefore, it is always vital to check your fluid for contamination and change it and or improve fluid filtration when required.

After troubleshooting overheating problems, if you have determined it is not due to the four common causes mentioned above, then there are two general ways you can resolve fluid overheating problems. You can either increase the reservoir capacity to dissipate heat or decrease the amount of heat being generated by the system.

Another way to increase the heat dissipation is to inspect the current heat exchangers, if they are being used, and make the appropriate adjustments. In some cases, you may want to install additional heat exchangers to help reduce the fluid temperature.

In addition, check the airflow around the reservoir as the higher the airflow the more efficiently the reservoir radiates the heat from the fluid held inside it.

To find hydraulic parts, components, and accessories to help you resolve hydraulic oil overheating problems, or if you require assistance in troubleshooting system overheating, please feel free to contact White House Products, Ltd. at +44 (0) 1475 742500 today!

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Overheating ranks No. 2 in the list of most common problems with hydraulic equipment. Unlike leaks, which rank No. 1, the causes of overheating and its remedies are often not well understood by maintenance personnel

Heating of hydraulic fluid in operation is caused by inefficiencies. Inefficiencies result in losses of input power, which are converted to heat. A hydraulic system’s heat load is equal to the total power lost (PL) through inefficiencies and can be expressed as:

If the total input power lost to heat is greater than the heat dissipated, the hydraulic system will eventually overheat. Installed cooling capacity typically ranges between 25 and 40 percent of input power, depending on the type of hydraulic system.

How hot is too hot? Hydraulic fluid temperatures above 180°F (82°C) damage most seal compounds and accelerate degradation of the oil. While the operation of any hydraulic system at temperatures above 180°F should be avoided, fluid temperature is too high when viscosity falls below the optimum value for the hydraulic system’s components. This can occur well below 180°F, depending on the fluid’s viscosity grade.

To achieve stable fluid temperature, a hydraulic system’s capacity to dissipate heat must exceed its heat load. For example, a system with continuous input power of 100 kW and an efficiency of 80 percent needs to be capable of dissipating a heat load of at least 20 kW. Assuming this system has a designed cooling capacity of 25 kW, anything that increases heat load above 25 kW or reduces the cooling system’s capacity below 25 kW will cause the system to overheat.

Consider this example. I was recently asked to investigate and solve an overheating problem in a mobile application. The hydraulic system was comprised of a diesel-hydraulic power unit, which was being used to power a pipe-cutting saw. The saw was designed for sub-sea use and was connected to the hydraulic power unit on the surface via a 710-foot umbilical. The operating requirements for the saw were 24 GPM at 3,000 PSI.

The hydraulic power unit had a continuous power rating of 37 kW and was fitted with an air-blast heat exchanger. The exchanger was capable of dissipating 10 kW of heat under ambient conditions or 27 percent of available input power (10/37 x 100 = 27). The performance of all cooling circuit components were checked and found to be operating within design limits.

At this point it, was clear that the overheating problem was being caused by excessive heat load. Concerned about the length of the umbilical, I calculated its pressure drop. The theoretical pressure drop across 710 feet of ¾-inch pressure hose at 24 GPM is 800 PSI. The pressure drop across the same length of 1-inch return hose is 200 PSI. The theoretical heat load produced by the pressure drop across the umbilical of 1,000 PSI (800 + 200 = 1,000) was 10.35 kW. This meant that the heat load of the umbilical was 0.35 kW more than the heat dissipation capacity of the hydraulic system’s heat exchanger. This, when combined with the system’s normal heat load (inefficiencies) was causing the hydraulic system to overheat.

Hydraulic systems dissipate heat through the reservoir. Therefore, check the reservoir fluid level and if low, fill to the correct level. Check that there are no obstructions to airflow around the reservoir, such as a buildup of dirt or debris.

Inspect the heat exchanger and ensure that the core is not blocked. The ability of the heat exchanger to dissipate heat is dependent on the flow-rate and temperature of both the hydraulic fluid and the cooling air or water circulating through the exchanger. Check the performance of all cooling circuit components and replace as necessary.

An infrared thermometer can be used to check the performance of a heat exchanger, provided the design flow-rate of hydraulic fluid through the exchanger is known. To do this, measure the temperature of the oil entering and exiting the exchanger and substitute the values in the following formula:

For example, if the measured temperature drop across the exchanger is 4ºC and the design oil flow-rate is 90 L/min, the exchanger is dissipating 10 kW of heat. Relating this to a system with a continuous input power of 100 kW, the exchanger is dissipating 10 percent of input power. If the system is overheating, it means that either there is a problem in the cooling circuit or the capacity of the exchanger is insufficient for the ambient operating conditions.

On the other hand, if the measured temperature drop across the exchanger is 10ºC and the design oil flow-rate is 90 L/min, the exchanger is dissipating 26 kW of heat. Relating this to a system with a continuous input power of 100 kW, the exchanger is dissipating 26 percent of input power. If the system is overheating, this means that the efficiency of the system has fallen below 74 percent.

Where there is a pressure drop, heat is generated. This means that any component in the system that has abnormal, internal leakage will increase the heat load on the system and can cause the system to overheat. This could be anything from a cylinder that is leaking high-pressure fluid past its piston seal, to an incorrectly adjusted relief valve. Identify and change-out any heat-generating components.

A common cause of heat generation in closed center circuits is the setting of relief valves below, or too close to, the pressure setting of the variable-displacement pump’s pressure compensator. This prevents system pressure from reaching the setting of the pressure compensator. Instead of pump displacement reducing to zero, the pump continues to produce flow, which passes over the relief valve, generating heat. To prevent this problem in closed center circuits, the pressure setting of the relief valve(s) should be 250 PSI above the pressure setting of the pump’s pressure compensator (Figure 1).

Continuing to operate a hydraulic system when the fluid is over-temperature is similar to operating an internal combustion engine with high coolant temperature. Damage is guaranteed. Therefore, whenever a hydraulic system starts to overheat, shut it down, identify the cause and fix it.

Brendan Casey has more than 20 years experience in the maintenance, repair and overhaul of mobile and industrial equipment. For more information on reducing the operating cost and increasing the...

Make sure that the Tailstock Rapid solenoid is not engaged when you adjust the Tailstock pressure. Press [RESET] twice after you release [EMERGENCY STOP].

Replace the 10A breaker with a 15A breaker. Only replace the breaker after all other causes have been checked and eliminated. Refer to the PSUP PCB Troubleshooting Guide.

Note: There is a long set screw snubber in the manifold behind the gauge and a 10 micron sintered bronze snubber in the gauge. These components protect gauges from failing during large pressure changes and slow the pressure gauge’s response to pressure changes or coming up to pressure from idle. These pressure changes are happening quicker at the chuck or tailstock then at the gauge or gauge page. The higher the pressure and warmer the oil, the faster the gauges will respond to pressure changes.

Check electrical connections to the pressure switch or motor or for failed hardware such as the pressure valve, hydraulic motor, or coupler. See the Programmable Pressure Adjustment Valve - Troubleshooting Guide for more information.

If the oil tank overflows, find the cause, and fill the oil to the correct level. If the oil is contaminated with coolant, drain and replace the oil (refer to the Coolant Contamination section).

Make sure the hoses are routed correctly [4] and are secure. Tie them together with zip ties [3]. Damage can occur to the hoses if they rub [1] against other components, have sharp bends, or are kinked [2]. Replace the hoses if they are damaged.

Check the condition of the hydraulic hose fittings: Look for leaks at both ends of the hose. If a leak is found, try tightening the fittings. Refer to Lathe - Hydraulic Power Unit (HPU) - Hoses and Fittings - Maintenance. If a fitting has cracks [5], wear, continues to leak, the hose must be replaced.

Make sure Setting 216 SERVO AND HYDRAULIC SHUTOFF is set to (120) seconds or less. Do not have this setting set to (0), the HPU will not turn off, and will create unwanted air bubbles and heat. This setting will power-down the HPU when the machine is idle. This helps dissipate the air bubbles in the oil.

Machines with the Classic Haas Control with software version 11.27A or higher and all Next Generation Control machines do not allow you to set this setting to (0). The limits on this setting for these machines are 10 seconds to 99 minutes.

Check for oil leaks at the intake pipe [1]. If there are leaks, clean the threads on the intake pipe [1]. Reapply thread sealant, and install the intake pipe [1].

Push[EMERGENCY STOP]. Wait half an hour while the air and oil separate. Resume machine operation. Check if the normal pressure returns while the operation resumes. If the symptom occurs again:

Note:If low pressure alarms are generated or the hydraulic pressure gauge comes up to pressure very slowly, it can be due to cold oil and/or a lower pressure setting. There is a long set screw snubber in the manifold behind the gauge and a 10 micron sintered bronze snubber in the gauge. These components protect gauges from failing during large pressure changes and slow the pressure gauge’s response to pressure changes or coming up to pressure from idle. These usually happen when the tailstock is reversing direction. These pressure changes are happening quicker at the chuck or tailstock then at the gauge or gauge page. The higher the pressure and warmer the oil, the faster the gauges will respond to pressure changes.

Check the gauge [1] or dipstick [2] to make sure that the HPU has enough oil. If the oil level is low, check for a leak. If there is a leak, repair the leak. Refill the oil.

If the machine has a heat exchanger, make sure the heat exchanger is clean and its fan operate correctly. Not all heat exchangers have a separate fan. Some machines have remotely-mounted heat exchangers with integral fans.

The spindle fan on machines with the Classic Haas Control with software version 11.27A or higher and all Next Generation Control machines must stay on when the HPU is on.

Check the adjustment valve for debris: With the HPU powered on, open and close the adjustment valve fully to flush any contamination out. Power off the HPU and remove the adjustment valve. Inspect the o-rings for damage. Damaged o-rings can also cause incorrect pressure.

If the adjustment valve is damaged, replace it. For adjustment valve replacement instructions, refer to the ST/DS Lathe - Chuck and Tailstock Pressure Adjusting Valve - Replacement procedure.

An ST-10/15 can have the Rapid Tailstock solenoid engaged when the tailstock is not in use. Press[RESET] twice after you release [EMERGENCY STOP] to disengage the solenoid and the pressure can be adjusted.

Find the coolant return line under the spindle. If chips block the coolant return line, coolant floods into the hydraulic union and will contaminate the HPU oil and cause it to foam. It can also cause the tank to overfill.

Drain the HPU and blow shop air through the hoses. Clean or replace all HPU filters. Clean the HPU and refill it with new oil. Cycle the chuck and tailstock several times. Check the oil again.

Remove the elbow fitting [1] from the intake line [2] and the intake filter [3]. Install the new intake screen [4] (Haas P/N 58-1832) on a new nipple (available locally). The new nipple length must be long enough so the new intake screen [4] is 1/4" from the bottom of the tank.

Remove the return line [5] from the return drain [6]. Install an elbow fitting [7] between the return line [5] and the return drain [6]. Install a new pipe nipple (available locally) to the elbow fitting [7] that reaches approximately 1" from the side of the tank.

The power supply PCB has a phase detect with neon indicators on the top center portion of the board. Make sure that the electrical power is phased correctly:

Remove the pressure gauge and check that the snubber set screw [1] has not backed out. The snubber set screw is similar to the Haas Liquid Grease restrictor fitting. Re-install the snubber set screw without any thread locker. Replace the gauge as needed.

In this Haas Service Video, Haas Service Engineer Andrew Harnett walks you through how to troubleshoot an HPU on a Haas ST lathe. If your HPU is noisy and pressure is fluctuatiing, before you assume the unit is bad you need to see this video.

WARNING: You should not do mechanical or electrical machine repairs or service procedures unless you are qualified and knowledgeable about the processes.

All information herein is provided as a courtesy for Haas machine owners for reference and illustrative purposes only. Haas Automation cannot be held responsible for repairs you perform. Only those services and repairs that are provided by authorized Haas Factory Outlet distributors are guaranteed.

Based on polls I’ve conducted with my Hydraulics Pro Club members over the years, overheating ranks number two in the list of most common problems with hydraulic equipment. But unlike leaks, which rank number one, the causes of overheating and its remedies are often not as well understood. With the northern summer rapidly approaching, now is a good time for a little revision.

Heating of hydraulic fluid in operation is caused by inefficiencies. Inefficiencies result in losses of input power, which are converted to heat. A hydraulic system’s heat load is equal to the total power lost (PL) through inefficiencies and can be expressed as PLtotal = PLpump + PLvalves + PLconductors + PLactuators.

If the total input power lost to heat is greater than the heat dissipated, the hydraulic system will eventually overheat. Installed cooling capacity typically ranges between 25% and 50% of continuous input power, depending on the type of hydraulic system and its application.

Hydraulic fluid temperatures above 82°C (180°F) damage most seal compounds and accelerate degradation of the oil. While the operation of any hydraulic system at temperatures above 82°C should be avoided, as I explained in my previous column, fluid temperature is too high when viscosity falls below the optimum value for the hydraulic system’s components. This can occur well below 82°C, depending on the fluid’s viscosity grade (weight).

To achieve stable fluid temperature, a hydraulic system’s capacity to dissipate heat must exceed its heat load. For example, a system with continuous input power of 100 kW and an efficiency of 80% needs to be capable of dissipating a heat load of at least 20 kW. Assuming this system has an installed cooling capacity of 25kW, anything that increases heat load above 25 kW or reduces the cooling system’s capacity below 25kW will cause the system to overheat.

Consider this example. I was asked to investigate and solve an overheating problem in a mobile application. The hydraulic system comprised a diesel-hydraulic power unit, which was being used to power a pipe-cutting saw. The saw was designed for sub-sea use and was connected to the hydraulic power unit on the surface via a 710-ft umbilical. The operating requirements for the saw were 24 gpm at 3,000 psi.

The hydraulic power unit had a continuous power rating of 37 kW and was fitted with an air-blast heat exchanger. The exchanger was capable of dissipating 10 kW of heat at the prevailing ambient conditions at the work site or 27% of available input power (10/37 x 100 = 27). The performance of all cooling circuit components were checked and found to be operating within design limits.

At this point it was clear that the overheating problem was caused by excessive heat load. Concerned about the length of the umbilical, I calculated its pressure drop. The theoretical pressure drop across 710 feet of 3/4″ pressure hose at 24 gpm is 800 psi. The pressure drop across the same length of 1″ return hose is 200 psi. The theoretical heat load produced by the pressure drop across the umbilical of 1,000 psi (800 + 200 = 1,000) was 10.35 kW. This meant that the heat load of the umbilical was 0.35 kW more than the heat dissipation capacity of the hydraulic system’s heat exchanger. This, when combined with the system’s normal heat load (inefficiencies), was causing the hydraulic system to overheat.

Hydraulic systems dissipate heat, albeit a relatively small amount, through the reservoir. Therefore, check the reservoir fluid level and, if low, fill to the correct level. Check that there are no obstructions to airflow around the reservoir, such as a build-up of dirt or debris.

As the long-umbilical story above illustrates, where there is a pressure drop, heat is generated. This means that any component in the system that has abnormal internal leakage will increase the heat load on the system and can cause the system to overheat. This could be anything from a cylinder that is leaking high-pressure fluid past its piston seal to an incorrectly adjusted relief valve. So identify and change-out any heat-generating components.

A common cause of heat generation in closed-center circuits is the setting of relief valves below, or too close to, the pressure setting of the variable-displacement pump’s pressure compensator. This prevents system pressure from reaching the setting of the pressure compensator. Instead of pump displacement reducing to zero, the pump continues to produce flow, which passes over the relief valve, generating heat. To prevent this problem in closed-center circuits, the pressure setting of the relief valve(s) should be 250 psi above the pressure setting of the pump’s pressure compensator (Fig. 1).

Continuing to operate a hydraulic system when the fluid is over-temperature is similar to operating an internal combustion engine with high coolant temperature. Damage is guaranteed. Therefore, whenever a hydraulic system starts to overheat, shut it down, identify the cause, and fix it.

Brendan Casey is the founder of HydraulicSupermarket.com and the author of Insider Secrets to Hydraulics,Preventing Hydraulic Failures, HydraulicsMade Easy and Advanced Hydraulic Control.A fluid power specialist with an MBA, he has more than 20 years experience in the design, maintenance and repair of mobile and industrial hydraulic equipment. Visit his Web site: www.HydraulicSupermarket.com.

Allen Mills, President of HyFlex, took some time out on a jobsite to walk through winterizing a hydraulic pump manifold. Watch the video or read the step-by-step process below!

Winterizing a pump takes about three minutes and is really simple. The pump in this video will be sitting outside overnight in 25 degree weather so we needed to do this procedure. I"ve taken the discharge manifold off of the valve bodies and sat it to the side with the upper check balls. There are eight nuts that were removed to accomplish this.

After removing the upper check balls, you will see the valve bodies full of water most likely. Remove the clamp or camlock connecting the hopper to the intake manifold. Then you can take your wrench or screw driver and place it in the valve body to push the lower check ball to the side to allow the water to drain out. Do this for each side.

Now the discharge manifold, valve bodies, cylinders, intake manifold, and hopper are all drained for cold weather. Alternatively some crews will dump a gallon of RV antifreeze in the hopper and cycle the pump to ensure it is drawn into both cylinders.

The reason this is really important (and we see this a lot in the wintertime) - these pumps, if they get left with water in them, what can happen is the connecting rod that"s back in the transfer box can actually bend because as the water expands when it freezes, it can push that back.

This unit has the bigger electric motor. You can see it"s a lot larger. You can see there"s a fan on the back of it, but there"s no cooler on the back of the motor.

So to cool the hydraulics we have a water-cooled heat exchanger down below. Occasionally we will have a customer forget to drain these or leave a water hose connected to them in cold weather. Normally the 321E"s are used inside, but heat still gets shutoff occasionally over night or on a weekend and it is a good idea to drain the cooler and disconnect the water hose.

And what the easiest way to do this is if you put an air gun on the back, on this water hose, open the valve and then just blow air through it until the water comes out.

Air that enters a hydraulic system can cause many problems that could subsequently lead to system failure. Here FPE Seals discusses how to spot these potential problems and why it is so important that air is bled from a system as soon as it is detected.

Essentially, hydraulic pumps are not designed to pump air because when compressed air generates heat. When air contaminates a hydraulic fluid, usually via the pump’s inlet, aeration, cavitation, or foaming can occur.

Aeration is bad news, as it degrades the hydraulic fluid causing damage to the components of the system due to loss of lubrication, resulting in overheating and burning of the seals. Overheating is particularly dangerous as dieseling can occur when the hydraulic cylinder oil mixes with the air, causing an explosion under compression.

Cavitation, brought on by the rapid changes of pressure in the fluid, causes small vapour-filled bubbles to contaminate the system, which implode when compressed. Ultimately this leads to metal erosion, which harms the system’s components and contaminates the fluid.

Abnormal noise is often a tell-tale sign that there is trapped air in a hydraulic system. As air circulates through the system it compresses and decompresses, creating a banging or knocking noise.

This is why abnormal noise must always be checked out and careful inspection given to the condition of the system’s fluid, components and seals, to identify any signs of trapped air or contamination.

It is also important that displacement hydraulic cylinders are bled before installation as any air trapped in the system would work like a gas shock absorber. For this reason, displacement cylinders have a breather at the top, to disperse any air.

And lastly, when testing a new cylinder, it is important to check for potential air contamination, as this can result in blowing the dirt wiper and the hydraulic seal out of its housing extruding past the rod.

All things considered, if spotted early and dealt with quickly, bleeding trapped air in a system, will prevent any long-term damage or operational downtime.

Commercial high pressure pumps used for agricultural, commercial cleaning, pest control, and other industries have a lot of moving parts. Those parts inevitably make some noise.

Some plunger pump noise is acceptable, but there are times when high noise levels indicate that something is wrong. Noises that begin suddenly or increase in volume over time might indicate one of the following problems and be a sign that it’s time to do some critical pump maintenance to achieve pump noise reduction.

A rattling sound inside a pump may be caused by damaging cavitation, resulting from imploding internal gaseous bubbles due to restricted flow, improper pressure, or other issues. Likewise, water hammering, a single implosion of a large gaseous bubble or air pocket might sound like a loud bang. Take steps to eliminate cavitation.

If a pump’s seals are going bad, cracked, or dried out, they can form leaks. Air leaks in inlet plumbing can create very loud noises. Similarly to cavitation, it can ruin a pump if not corrected. Check all the connections regularly to verify a proper seal.

If you have a big plastic housing that has a built-in tank, or hoses that run loosely along the floor of the plastic housing and you place a pump on top of it, it will likely result in excessive noise. Likewise, any hose that’s not routed in a way that keeps it away from the walls and housing could cause issues.

If a pump is nearing the end of its life, the plunger slot and cam bearing that’s attached to the end of the motor can wear out. Proper maintenance can help avoid this issue.

Particulates in the lubricant could scratch and damage a pump system, resulting in noise. A lack of preventative maintenance or a dirty environment can cause issues and even lead to a loss of lubricating grease. Water contamination could cause connecting rods to open up. The pump will knock like a car engine, especially with the change of speed/load and the starting and stopping of the motor.

Many pumps use an oil bath that will drain out if the pump is not kept upright. The resulting low oil levels will cause the pump to wear out and could even cause the connecting rod to blow out the top of the pump. Pumptec pumps do not use an oil bath and can run in any orientation and be stored on their sides, so no worries.

Pulsation can occur in hoses that are too weak, too long, too rigid, or too soft, causing a drumming sound. Using a pulse hose can help to minimize pulsations due to its ability to dissipate energy and built-up pressure, smoothing the flow of liquids.

If a pump isn’t properly secured to the equipment, it can cause components to rattle or bang around. Use rubber vibration isolation mounts to dampen the impact and make sure all fittings are tightened.

If you have a check valve that’s plugged or worn out, you can lose flow from one head of the pump, cutting flow in half. In this case, only one side of the pump is working and will cause a noticeable pulsation.

While not a problem, high flow — especially at low pressure — is more prone to noise and should be expected at some level. As you go up in performance, especially flow, you’ll get more noise. Higher flow rate pumps have larger plungers with more movement because the cam is offset farther than with smaller pumps, creating more vibration and noise.

What if you feel like the pump is too noisy right out of the box? The type of pump and the desired performance will help inform what an acceptable decibel level should be. An electric or battery-powered pump should have a consistent hum and will generally operate around 80-85 dB or lower. Some gas-powered pumps can be over 100 dB due to their internal combustion engines, requiring hearing protection. The benefits of electric vs. gas-powered pump noise levels are easy to see.

A centrifugal pump is typically the quietest because it doesn’t have parts changing direction; it mostly has a fan that spins. But it’s also the least efficient, requiring four times as much horsepower as a plunger pump to achieve the same GPM and PSI.

Diaphragm pumps are also quiet because valves are usually made of rubber. However, to achieve high pressure that compares with plunger pumps, valves need to be manufactured out of rigid materials like stainless steel which produce a mechanical noise.

Plunger pumps may have a slightly higher noise level than standard centrifugal or diaphragm pumps, but are often much more suited to commercial uses that require long-lasting durability and precise flow and coverage.

But the hard truth is that it’s difficult to pinpoint acceptable pump noise levels due to the subjective nature of defining noise. The location or setting where a pump is operated might inform someone’s opinion of whether a pump is too noisy. For example, a certain decibel level might be acceptable in an agricultural setting, but seem too loud in a residential neighborhood.

The standard decibel rating that is published in product manuals requires laborious tests under highly controlled environments and conditions. Sometimes these official tests take place in soundproof booths, require calibrated microphones and equipment, or are a result of multiple samples taken from several directions, distances, and heights that are all averaged together.

The problem is that an operator with a decibel reader app on their iPhone isn’t following those rules or operating their pump in such a controlled environment. They might hold their phone a foot away from the pump on the back of their pickup truck and be frustrated that it exceeds the stated rating that was taken at a 3-meter distance in a soundproof booth. Their meter reading will inevitably be inconsistent with those published in the owner"s manual, but it may, in fact, be operating exactly according to specifications.

Pumps also come in different models and may be rated at specific performance levels using certain nozzles. There’s no guarantee that the operator will run it at the same performance level or with the same accessories.

As you can see, decibel ratings are sometimes a moving target. Unless your pump is experiencing some of the problems noted earlier, your pump may be operating exactly as designed.

Of course, you could choose a pump model rated at lower decibel levels, but there are trade offs to consider. Will reducing pump noise inevitably lead to reduced power, flow, and overall performance? Are there pumps that deliver quieter operation but fail to hold up over time?

It’s important to consider all the factors when gauging noise levels, including desired GPM and PSI. For more information on industry standards for pump GPM and PSI, be sure to check out our free guide below.

A small amount of noise may be acceptable if you’re getting the power, flow, and performance you need. At Pumptec, our pumps are sought after for their quiet yet powerful performance. If you have questions about pump noise levels or want to explore replacing your current pump systems, contact our pump experts today.

A hydraulic system works under three key principles: A liquid can’t be compressed; resistance to flow is the only way to create pressure in a system; and energy created under pressure will yield either work or heat.

The heart of a hydraulic system is a positive-displacement pump that is either of a fixed-displacement or a variable-displacement style. Either of these pump styles can be a gear, a vane, or a piston design.

On the other hand, a variable-displacement pump can alter the volume of oil it moves with each cycle even if the operating speed stays the same. This design is employed in applications where a specific pressure or flow must be maintained.

Most early hydraulic systems used on tractors were open-center designs. As farmers grew more dependent on hydraulics, their systems advanced to a closed-center system and finally to a load-sensing system.

With an open-center system, the pump produces a continuous flow of oil that must return to the reservoir when the cylinder or other actuator is not being moved. When flow is directed via a control valve to a cylinder, the oil volume stays constant. However, the oil pressure is increased to the level necessary to perform the work.

When the control valve is released, the fluid remains trapped in the cylinder, and the workload is supported. The pump pressure goes down and flow increases.

Pump displacement and, thus, flow, changes to meet the demand required. When no function is required, oil flow is blocked at the control valve. When one (or more) control valve is opened, the pump automatically adjusts the delivery rate (volume) to satisfy the demand. Pressure to the valves will be maintained as long as the pump volume is sufficient to meet the demand.

Today, it is common to find a load-sensing system in use on tractors, particularly high-horsepower models. It is a modification on the closed-system design. This design permits stand-by pressure to be low when the control valve is in neutral.

When you move the control valve, flow is designed to maintain a pressure slightly higher than the highest pressure needed in the system. It regulates flow based on the pressure required to move the load rather than based on the pump output.

One reason for this is that this oil does more than perform work. It must lubricate moving parts, be chemically stable at high temperatures and pressures, protect parts from rust and corrosion, resist foaming and oxidation, and be capable of separating itself from air, water, and other contaminants.

Hydraulic oil must also maintain a designated viscosity while operating in a wide temperature range. Viscosity is a fluid’s resistance to flow. It is the thickness at a defined temperature set by the Society of Automotive Engineers.

All petroleum-base oils tend to thicken when they are cold, and they become thinner when heated. If the viscosity is too low (or thin), it can cause leakage past the seals. But if the fluid is too thick (high viscosity), sluggish operation of the hydraulics occurs along with an additional power drain on the engine.

For example, an oil will be given a low viscosity index if it becomes very thick at low temperatures and very thin when heated. A high viscosity index describes fluid that remains relatively stable in thickness as it is heated or cooled.

Farm equipment hydraulic systems are fitted with components that have very tight and exacting tolerances. As a result, they require hydraulic oil that has a high viscosity index and also has lubricating qualities paramount to long life. Good oil will be able to cling to close-fitting parts even under high temperatures. Many tractors use the hydraulic oil to lubricate the transmission. Low-quality hydraulic oil will provoke excess wear in the hydraulics and transmission.

Ensuring a smooth operating hydraulic system is quite basic. You need to remember that hydraulic oil does wear out over time and needs to be changed. Often the additives in the oil (which are essential to its performance) become consumed. Plus, oil also absorbs dirt and moisture over time, compromising its ability to perform, let alone prevent corrosion of key components, seals, and gaskets. One sign of worn-out oil is components that stick when operating. This is especially true of control valves.

When purchasing hydraulic fluid, make sure the brand meets or exceeds the requirements for your machine as dictated in the owner’s manual. Equipment manufacturers have application-specific requirements for the oil. Even though you may save a few dollars selecting a cheaper oil, it may cost you in the long run. That same advice is true when selecting hydraulic filters.

When buying fluid, only purchase what you need for that season, because hydraulic oil can get old (their additives can precipitate out of the oil with time). Be sure to always store fluids in a shop that has minimal temperature variation to avoid condensation from forming in the storage container and polluting new oil.

From time to time, listen to the hydraulic system operation and watch how well it performs. These efforts can tell you that something is going wrong long before a major problem occurs.

Proper service intervals are meaningless if a hydraulic system isn’t kept clean. Always use the dust caps on coupler valves and wipe off any fitting or service port before opening up or closing.

Keep the hydraulic system’s exterior clean by simply washing with a pressure wash, as dirt left around seals and dipsticks eventually work into the fluid.

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Dad was a lot of things, but he was no hydraulic expert. However, that doesn’t mean he (and everyone else) didn’t have an opinion on hydraulic oil. The problem with opinions is that they come from persons with enough knowledge that people listen—but enough knowledge to be potentially dangerous with misinformation. Here are five critical things your father never told you about mobile hydraulic fluids.

1. Hydraulic fluid serves more than one purpose.Hydraulic fluid’s primary purpose is to transmit hydraulic energy in the combined form of pressure and flow. For all intents and purposes, hydraulic fluid can be considered solid and nearly incompressible as it acts upon pistons of cylinders and gears/pistons/vanes of motors. The hydraulic pump pushes on fluid, and the fluid pushes on the actuators; this is the easily understood nature of fluid in a hydraulic system. However, transmission of mechanical force is not the only trick in its bag.

Contamination removal, heat transfer, sealing and lubrication are all important secondary properties of hydraulic fluid. Although these properties are innately functional within hydraulic oil, considering them as part of the design or maintenance of mobile machinery will help you get the most out of your system.

Contamination removal in hydraulic fluid is the most commonly considered of the secondary properties. Everyone knows dirt needs to be removed from oil, which is why every mobile machine has at least one hydraulic filter on it (typically a poor-quality one, which is something your father never told you about filtration). Although estimates vary, everyone agrees contamination is the number one cause of failure of pumps, valves and actuators on mobile machines, even ahead of physical damage.

Hydraulic fluid helps control contamination pretty much by default, because it circulates through every component you’re trying to protect. As contamination is either externally- or internally generated, it will be picked up in the fluid stream and carried back to where it can be trapped by the filter(s). We can ensure we take advantage of the particle-transportation properties of fluid by trapping as much as possible in strategic locations. You should use a high quality return line filter and a pressure filter mounted after the pump. Because pumps are a common failure point, their degradation will not result in more contamination being transmitted to every other component in the system when a pressure filter is installed.

Heat transfers efficiently through a liquid, making it an excellent tool for convection of thermal energy. Anywhere in a hydraulic system where hydraulic energy is not being used to create useful work, the by-product is heat. The major heat generators are pumps, motors and relief valves. Because heat reduces the viscosity of the fluid, it needs to be carried away from components and cooled if it reaches high temperatures. Although the fluid carries heat with it by default, just as with contamination, you must take advantage by sizing reservoirs appropriately, and by adding a cooler when heat generation is high.

Sealing between static components is almost exclusively handled by soft seals, such as O-rings. Dynamic sealing is also most often done with soft, mechanical seals, but not only does hydraulic fluid aid in sealing, it can also be the seal medium itself. Lip seals, for example, use the pressure of the fluid to push the lips against the sealed surface, further enhancing seal efficiency. However, because of hydraulic oil’s resistance to shearing, the oil itself is used to seal close-tolerance moving bodies, such as the spool and housing of a directional valve, or the piston and cylinder block of a pump. By ensuring your hydraulic fluid is in its most effective viscosity range, you also ensure the fluid will properly seal in these components.

Lubrication is probably the second most important quality of hydraulic fluid. It enables all the various internal components of pumps, motors, valves and cylinders to move against one another efficiently and reliably. If your hydraulic fluid loses its lubricity, such as with overheating or excessive water saturation, component damage is not far behind. Most mobile hydraulic systems use oil, which has natural lubrication qualities. But when applying less common fluids such as “arctic” or bio-oils, these additive packages provide excellent lubricity.

2. Oil does not need to be changed very frequently.Hydraulic oil in your backhoe is not the same as engine oil in your car. Hydraulic oil isn’t exposed to the same abusive conditions experienced by automotive engine oil, such as >2000° combustion temperatures, soot ingression from incomplete burn, and excessive contamination from wear particles, water or fuel.

Under normal conditions, a well-maintained hydraulic system’s oil can last indefinitely. Hydraulic oil breaks down with extreme heat, excessive water saturation and oxidation. Further, conditions such as high water content and heat also exacerbate the oxidation. High heat also reduces viscosity, which if low enough, will allow metal-to-metal contact, generating internal contamination.

However, if oil is clean, cool and free from water, the chemistry to break it down does not exist, and it remains in the same state as it was poured into the reservoir. If anything, some of the additives, such as zinc, can deplete over time, so keeping an eye on your fluid through an oil-analysis program will ensure you’re within operating parameters.

Manufacturers of tractors and other off-highway machinery will publish required hydraulic oil change periods, which are the longest of any of the fluid in the machine. However, some newer and larger tractors have no published hydraulic oil change interval, which could be related to the overall design of the machine, including measures to ensure heat, water and particle contamination are kept to a minimum or avoided altogether.

3. Not all hydraulic fluid is the same.Hydraulic fluid varies just as much as the fluids in your car. Hydraulic fluid can come from conventional oil, but it can also be formulated from synthetic stock. Hydraulic fluid can also be glycol-based, a water/glycol mix, or even nearly 100% water in some applications.

Luckily, most hydraulic fluid used in mobile machinery is the standard “decomposed dinosaur” type, made from the same stock as your 10w30 engine oil, but with a slightly different additive package. However, hydraulic oil varies enough that you should be careful selecting the appropriate type for your application.

Viscosity is the most important consideration, and is important enough to have a noticeable effect on machine performance. If you had an oil-spill on a winter morning and sent your farm-hand down to the Co-op to grab a pail, and he comes back with AW68, you could see sluggish operation because of the high viscosity.

The quality of oil differs greatly as well, and just like engine oils, synthetic hydraulic oil is far superior. Synthetic oil has higher viscosity index, better lubricity and a lower pour point than regular oil. Synthetic oil will perform better in a wider range of conditions, last longer and generally provides peace of mind knowing it’s providing extra protection for your expensive machine.

Automatic Transmission Fluid is used in everything from a Fiat 500 to a Ford F-150, and because of the astounding service life required by vehicle transmissions, the fluid used is some of the most high-quality lubrication available. ATF experiences such extremes in temperature, humidity and viscosity, yet can last 30,000-60,000 miles or more.

ATF is formulated for high viscosity index (the ability to maintain test viscosity over a wide temperature range), and has excellent water control properties, allowing the fluid to hold more water in saturation before being released to create corrosion. Also, the additives in ATF are formulated to improve lubricity, anti-foaming, shear stability and resistance to oxidation.

ATF is a premium hydraulic fluid, but also comes at a premium price, which is its major downside. A gallon of ATF i