volvo penta hydraulic pump free sample

Up for sale is an excellent  working condition Volvo Penta Hydraulic tilt & trim pump aq 290 Dp-a Dp-C at least that"s  what it was operating when we pulled it  from  the boat . Motor and pump  100% tested and fully operational with relays and wiring  . Bolt it on Get  back on the water!-

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With more than a million of their trucks on the road today, Volvo Trucks® is among the world’s trusted names in medium to heavy duty trucks. A division of the automaking giant Volvo Group, Volvo Trucks offers complete transport solutions for a wide range of industries, with manufacturing facilities across 13 countries and 2,300 service points across the globe. They also offer genuine replacement parts that are manufactured under the same uncompromising standards as their stock counterparts. Each genuine Volvo Truck component is also tested both in the laboratory and in the field. From freezing winters to the desert heat, customers can rest assured that their Volvo Truck parts will run reliably even under such conditions.

VPentaStore.com is the top destination for Volvo Penta Parts and Accessories. We carry a wide range of OEM and Aftermarket parts, ensuring that you"ll find what you need to keep your engine running smoothly. We"re confident in our ability to provide the best possible service, and we stand behind our products 100%. If you"re looking for quality Volvo Penta Parts, look no further than VPentaStore.com!

Whoever wants to buy a motor yacht is often faced with the choice of the right drive. In addition to the size of the yacht, the type of use and performance, the buyer should also consider the various types of drive available on the market before making the purchase in order to avoid disappointment later on. What are the advantages of shaft systems, so-called sterndrives and a pod, specifically: the IPS system from Volvo Penta? SeaHelp gives an overview.

The term shaft system has only come into use since other types of propulsion, such as sterndrives, jet drives and outboard motors (the latter two will not be discussed in detail here), have been used in yachts and it has become necessary to differentiate between the various propulsion systems. The so-called propeller nacelles for large vessels (pods) also play no role here, with the exception of Volvo Penta’s smaller IPS system for recreational boating.

Gearboxes are often part of the shaft system. These serve to reduce the engine speed to achieve specific speeds for favorable drive efficiency. In addition, the gearboxes often have other outputs to drive generators or pumps; for example, powerful hydraulic pumps are required to operate the stabilizers; bow and stern thrusters must also be supplied.

In 2004, Volvo first presented the IPS (Inboard Performance System) propulsion system, which has since defined what is feasible in recreational boating at the highest technical level. The technology is based on pod propulsion, comparable to the propulsion systems of passenger ships, the propeller gondolas.

The distinguishing feature of Volvo Penta’s IPS propulsion system is the forward-facing, counter-rotating traction propellers that generate horizontal thrust. The drives are located in the aft section of the stern and are integrated directly into the hull. The Swedish propulsion system now consists of ten models and is superior to conventional shaft systems in terms of maneuverability, on-board comfort and performance.

Furthermore, CO2 emissions and fuel consumption are said to be 30 percent lower each, it is much quieter on board (minus 50 percent subjectively perceived noise minimization), and finally, valuable space on board is also saved due to the compact design and the way it is (externally) mounted. Note from Volvo: the data given here are approximate values for full gliders at cruising speed – compared to corresponding shaft systems.

Those who decide to install an IPS propulsion system on their yacht can also take advantage of the joystick introduced by Volvo in 2006: with the joystick in the helm, the boat can be turned with just one touch on the platter (Mercury offers something comparable for its Zeus system).

Volvo Penta recently unveiled its new Assisted Docking System (ADS), which combines proprietary software with the GPS-based Dynamic Positioning System and its own Inboard Performance System (IPS) into a complete package. The goal: to further enhance the boating experience, even when really rough docking conditions such as strong crosswinds and/or currents make maneuvering difficult.

The present invention relates to a servo-assisted steering arrangement for an element pivotable about a steering shaft, comprising, in a hydraulic circuit, a first hydraulic pump driven by a manual drive means, at least two double-acting hydraulic piston cylinder devices connected in tie hydraulic circuit, each having a cylinder chamber on either side of the respective pistons, said piston cylinder devices being connected between the pivotable element and another element and a second hydraulic pump coupled into the hydraulic circuit, said second hydraulic pump being driven by a drive motor, the hydraulic circuit being divided into two, at least essentially mutually separated first and second partial circuits with a first hydraulic pump in the first partial circuit and a second hydraulic pump in the second partial circuit.

GB 2 159 482, for example, discloses a servo-assisted steering arrangement of the above type for pivoting an outboard motor about a vertical steering axis. The steering arrangement comprises a pair of piston cylinder devices, which are mounted between the ends of a steering arm joined to the engine propeller rig and mounting brackets on the boat hull. The piston rod of one of the piston cylinder devices is mechanically joined to a valve slide in a control valve, the valve housing of which is joined to a steering arm connected to the propeller rig. The control valve thus forms a mechanical connection between the piston rod of the first piston cylinder device and the propeller rig. The cylinder chambers on either side of the associated piston communicate with a steering wheel pump, which, when the steering wheel is turned, pumps hydraulic fluid to one or the other cylinder chamber, depending on the rotational direction of the steering wheel. The circuit, including the steering wheel pump and the first piston cylinder device, forms a low pressure circuit which is separate from a high-pressure circuit in which the control valve is coupled between a motor-driven hydraulic pump and the second piston cylinder device.

When the steering wheel is turned, oil is pumped into one cylinder chamber in the associated piston cylinder device, and at the same time the opposite cylinder chamber is drained. Initially, this leads to a displacement of the valve slide from its closed neutral position to one of its open lateral positions, in which a communication is established between the motor-driven pump and the opposite cylinder chamber in the second piston cylinder device, which leads to displacement of the piston in the opposite direction, which in turn results in the valve housing being displaced in the same direction as the valve slide during the steering movement. As long as the steering wheel is turned, the slide and the housing move together with the slide in the open position. When the turning of the steering wheel and the slide movement stops, the valve closes after a short displacement of the valve housing relative to the slide. The system described thus has a mechanical feedback, which requires that the control valve be movable together with the piston rod of the associated piston cylinder device. One disadvantage of a system with this function, i.e. initial turning of the steering wheel only takes up play and does not result in any steering forces, is that the driver will experience a marked looseness in the system when turning the steering wheel. Another disadvantage is that the total length of the piston cylinder device and the control valve makes it necessary that the distance between the mountings in the boat hull and in the propeller rig be relatively large- which makes it impossible to use the service device described together with certain marine drive units, e.g. an outboard drive unit of the type shown in SE 501 147 (U.S. Pat. No. 5,562,508).

This is achieved to the invention by virtue of the fact that the partial circuits are so connected to the control valve means and to their individual pair of cylinder chambers that the flow in the first partial circuit is directed to one cylinder chamber of the associated pair of cylinder chambers via the control valve means, which at a predetermined pressure open the communication between the second hydraulic pump and one of the cylinder chambers of the associated pair of cylinder chambers, so that the pistons in the respective piston-cylinder devices are displaced in a direction dependent on the flow direction in the first partial circuit.

By controlling the flow from the steering wheel pump parallel to a steering cylinder and to the control valve, a maneuver pressure is achieved immediately in the cylinder striving to pivot the pivotable elements coupled to the cylinders. No play arises on the order of magnitude which is unavoidable in the described known system, in which the hydraulic cylinder coupled to the steering wheel pump only steers a slave cylinder. The servo-assisted steering arrangement according to the invention therefore provides the driver with a better steering feeling and control over the boat. Since the feedback between the steering cylinders, the control valve and the steering wheel pump is completely hydraulic, the control valve can be mounted wherever desired in the boat, which means that it will not, as with the control valve in the described known servo arrangement encroach on the space available for the steering cylinders.

A control valve of this type, which, in a control circuit for a steering device according to the invention, permits manual emergency steering in the event of pressure failure on the high pressure side, is characterized in that the valve slide in one of said two positions establishes communication between a valve housing inlet intended to be connected to the high pressure side in a hydraulic circuit, and one of two connections intended to be connected to individual pressure medium-actuated devices, at the same time as communication is established between the second connection and an outlet from the valve housing intended to be connected to the low pressure side of the hydraulic circuit, non-return valve means arranged in the valve housing permitting, if there is pressure failure on the high pressure side, flow from the low pressure side to the high pressure side when the pressure on the low pressure side exceeds the pressure on the high pressure side.

FIG. 1 shows an inboard/outboard drive 1 of Aquamatic® type, comprising a carrier or shell 2, intended to be fixed to the transom and seal against the edges of an opening of the transom. The drive 1 has a rig leg 3, which is pivotally suspended in a fork-like carrying element 4 via a shaft 5, the center axis 6 of which forms the steering axis of the drive. The fork element 4 is journalled at its upper end in the shell 2 for pivoting about a horizontal axis 7. At its lower end, the fork element 4 engages a pair of piston cylinder devices 8 arranged symmetrically about the shaft 5, only one of which being shown in the figure. In the example shown, the piston rod 9 of the respective device 8 is pivotally joined to the element 4 via a pin 10 in a bore 11 in the respective fork leg of the element 4, while each respective hydraulic cylinder 12 is pivotally mounted in the shell 2 via a pin 13. The piston cylinder devices 8 form so-called trim- and tilt cylinders, by means of which the angle of the rig lea 3 can be trimmed during operation and by means of the rig leg can be swung up out of the water when at rest.

Two hydraulic piston cylinder devices 20aand 20boriented symmetrically relative to the longitudinal plane of symmetry of the drive. are pivotally joined to the lower end of each leo 21 of the fork element 4 and the cavitation plate 22 of the drive. In the example shown, the cylinder 23 of the respective piston cylinder device 20 is joined to the respective fork leg 21 by means of a pin 24 while the respective piston rod 25 is joined to a mounting 26 on the cavitation plate via a pin 27,

The schematic drawing in FIG. 2 shows in cross-section a portion of a transom 30, where 31 designates its inside, 32 its outside and 33 a through-opening, against the edges 34 of which the shell 2 is sealingly fixed. In an opening 35 in the shell 2, a control valve 36 is sealingly fixed against the edges of the opening 35. The valve 36 communicates via lines 37 and 38 with a hydraulic pump 39 which is connected to a manual drive means (not shown in more detail here), e.g. a steering wheel, which, when turned, pumps hydraulic oil both to the control valve 36 and to and from cylinder chambers in the cylinders 20aand 20b, as will be described in more detail below with reference to FIGS. 3 and 4. The control valve 36 is also connected to a pressure line 40 from a hydraulic pump 41 driven by a drive motor (not shown) and via a line 42 to an oil reservoir 43, to which a suction line 44 to the pump 41 is connected. Oil can be pumped to and from cylinder chambers in the cylinders 20a, 20bvia the control valve and the hydraulic lines 45, 46.

FIGS. 3 and 4 show the control valve 36 with its hydraulic circuits in more detail. FIG. 3 illustrates the position of the components for driving straight ahead, when the pump 39 does not provide any flow or pressure. As can be seen in FIGS. 3 and 4, the control valve 36 has a valve housing 50, in which a valve slide 51 is displaceably disposed in a cylindrical bore 52. The slide 5l is joined to a piston rod 53 of the control piston 54. which is slidably disposed in a cylindrical bore 55. Cylinder chambers 56, 57 on either side of the control piston 54 communicate with the hydraulic pump 39 via the lines 37, 38. When the pump 39 does not produce any flow and there is not pressure differential over the piston 54, the springs 58, 59 keep the valve slide 51 centered in the position shown in FIG. 3, in which the pressure line 40 and the suction line 42, 44 of the pump 41 are short-circuited in the control valve in that a ring groove 60 of the slide 51 joins the pressure channel 61 of the valve with its return channel 62 to the oil reservoir 43.

In FIG. 4, the manual pump 39 is driven by turning the steering wheel (not shown) so that a flow occurs in the direction indicated by the arrows, resulting in a flow to and a pressure increase in the cylinder chamber 57 of the control piston 54 and a flow out of the opposite cylinder chamber 56. This in turn results in a displacement of the control piston 54 to the left-hand position shown in FIG. 4. The flow through the cylinder chamber 57 supplies hydraulic fluid to the right-hand cylinder chamber 70 of the hydraulic cylinder 20a, at the same time as the same volume is drained from the right-hand cylinder chamber 71 of the hydraulic cylinder 20bvia the cylinder chamber 56 of the control piston. The displacement of the valve slide 51, caused by the control piston 54, results in a ring groove 63 in the slide 51 joining the pressure channel 61 of the valve with the left-hand cylinder chamber 72 of the cylinder 20b, at the same time as a ring groove 64 in the slide 51 joins the left-hand cylinder chamber 73 of the cylinder 20awith a return channel 65 to the return line 42. Oil is thereby supplied under high pressure from the motor-driven pump 41 to the left-hand cylinder chamber 72 of the cylinder 20bvia a channel 61a, at the same time as oil is drained from the left-hand cylinder chamber 73 of the cylinder 20avia a channel 65a. In the cylinder 20athere is a relatively low working pressure created by the manual pump 39. This working pressure is equal to the control pressure on the control piston 54, but this pressure is also an operating pressure which provides a steering force contributing to the steering movement of the drive and is not only a pressure for controlling the control valve.

When the turning of the steering wheel stops and thus the flow from the steering wheel 39 ceases. there will occur a pressure equalization over the control piston 54. so that the springs 58, 59 will return the valve slide 51 to the neutral position, in which it short-circuits the high and low pressure sides of the high pressure pump 41. At the same time the connections of the cylinders 20a, 20bto the high and low pressure sides of the pump 41 are broken so that hydraulic blocking in the set position is obtained.

As can be seen in FIGS. 3 and 4, the valve housing 50 contains a non-return valve 76 between the valve pressure channel 61 and the return channel 65. The non-retum valve 76 is a safety valve making possible completely manual emergency steering if the high pressure pump 41 should fail. If, in the state shown in FIG. 4, a pressure failure should occur in the pressure channel 61, oil must be able to be supplied to the pressure channel 61 by another path than from the pump 41 for oil to be able to be supplied to the cylinder chamber 72 of the cylinder 20b, at the same time as the cylinder chamber 73 in the cylinder 20amust be able to be drained, when the pressure generated manually in the cylinder chamber 70 strives to displace the piston 74 to the left in FIG. 4. Otherwise the system will lock hydraulically. The non-return valve 76 permits overflow from the return channel 65 to the pressure channel 61 so that the piston 75 during its movement in the cylinder 20bcan draw oil via the non-return valve 76 from the return channel 65 via the pressure channel 61 to the cylinder chamber 72.

In the embodiment shown in FIG. 2, the low pressure circuit 37.38 between the pump 39 and the cylinders 20a, 20bis connected to the cylinder chambers 72, 73 on the piston rod side, while in the embodiment shown in FIGS. 3 and 4, the low pressure circuit 37, 38 is connected to the cylinders chambers 70, 71 on the piston side. The choice is dependent on what mechanical advantage is desired, i.e. weighing manual steering force and the number of rotations of the steering wheel to produce a certain steering deflection. The latter embodiment provides higher manual steering force but requires, on the other hand, more rotations of the steering wheel for a certain steering deflection of the drive unit. In an alternative embodiment shown in FIG. 7, the low pressure pump 39 is connected to both cylinder chambers 70, 73 of one cylinder 20a, and the high pressure pump 41 is connected via the control valve to the two cylinder chambers 71, 72 of the second cylinder 20b. In this embodiment, at least the cylinder 20aon the low pressure side requires a piston 74 with piston rods 25 in both cylinder chambers, to obtain the same effective piston area on both sides of the piston. A certain minor leakage can be allowed between the high and low pressure sides without risking the function.

As can be seen in FIG. 2, the control valve 36 is mounted in an opening in the shell 2, so that its outside is subjected to water spray. This design allows the valve 36 to serve as an oil cooler for the hydraulic oil in the system and, at least in certain installations, it can completely replace a separate oil cooler. In order to increase the cooling capacity of the control valve 36, it can be provided with cooling flanges 80 as shown in FIG. 5 or, as shown in FIG. 6, it can be made with a channel 81 extending through the housing 50 and having at each end connections 82 for coolant hoses 83 to the engine coolant. The channel 81 can possibly also be provided with cooling flanges 84.

Generally, the support and lower units are provided with piston-cylinder units connected to a suitably pressurized fluid supply for trim adjustment. Additionally, hydraulic shock absorbing and energy dissipating piston-cylinder units are employed to permit tilt of the lower unit in response to striking of an underwater obstacle and the like without damage to the boat or motor. Further for trailering and maintenance, the propulsion device is tilted upwardly to a clearance position. Various systems have been suggested employing separate trim position units and shock absorbing units.

Generally, known functioning units suitable shock valve means connected in the system to compensate for timed energy forces under impact. For example, an energy absorbing relief valve means may be provided in the pump unit. Because of the large forces and pressures encountered, however, the size, shape, and structure of the hydraulic lines and connections becomes critical. The hydraulic system normally includes flexible lines or hoses for convenient interconnection of an inboard reservoir and pump means to the hydraulic actuator. Such lines are inherently subject to expansion and contraction under the required high pressures which may adversely affect the system operation. In addition, very large high strength lines are required. A highly desirable system employs a dual acting piston-cylinder unit for trim positioning, trailering positioning, and shock absorbing. The use of a combined shock absorbing and a trim positioning cylinder unit minimizes the number of components thereby minimizing the hardware and undesirable aesthetics associated with the multiple component systems. An extremely satisfactory system is disclosed in the copending application entitled "HYDRAULIC POWERED TRIM AND TILT APPARATUS FOR MARINE PROPULSION DEVICES" of Hale et al, which was filed on Sept. 4, 1975, the same date as this application, bearing Ser. No. 610,318 and assigned to a common assignee herewith. As more fully disclosed in such application, the combined trim, tilt, and shock absorbing means is provided mounted within the bracket assembly for aesthetic purposes and also to protect the components and particularly the hydraulic connections.

In order to permit the various functions under optimum conditions relatively complicated hydraulic systems and multiple cylinder arrangements have been generally employed.

The present invention is particularly directed to a hydraulic system for operating of a combined power trim and shock absorbing piston-cylinder unit for the tilting of the lower unit of a marine propulsion means, such as an outboard motor, a stern drive unit and the like which provides a reliable, long life protection and allowing rapid and accurated positioning of the lower units. The hydraulic supply apparatus of the present invention provides a highly favorable trail-out construction which permits movement of the propeller unit over obstructions at low speeds in a forward direction as well as addditional mechanisms permitting convenient manual tilting. Further, in accordance with a preferred and novel construction the apparatus is constructed and connected to introduce "memory" into the system such that after tilting either because of "trail-out" manual tilt or high speed impact tilting, the propulsion unit, returns to the previously set trim position.

More particularly, in accordance with the present invention, the trim and shock absorbing operator means is powered up and down from a pressurized reversible hydraulic source such as the conventional reversible pump. The source provides a trim-up port at one side and a trim-down port to the opposite side. The trim-up port is connected by a pressure responsive pilot valve means to the trim-up side of the trim and shock absorbing means to expand the unit and thereby effect the trim-up positioning. The opposite side or trim-down powered of the means is connected to return the fluid therefrom through a trim-down line including a reverse lock valve means, which is preferably an electrically operated normally open valve means providing a reverse lock functioning, and a down-pilot valve means to the supply or trim-down port of the source. The down-pilot valve means is preferably a spool type providing full flow under trim-up conditions and responsive to an increasing pressure at the trim-down side of the source to close the trim-up return path and pressurize the trim-down side of operation means through the reverse lock valve means. This provides for a full flow return path in the trim-up path and thereby avoiding the adverse effect of restrictions. With the source means establishing a trim-down output, the pilot valve means in the trim-up side of the source is actuated to positively hold the associated valve means open thereby permitting draining and return of hydraulic fluid from the opposite or trim-up side of the operator means and preventing a hydraulic lock of the operator means.

In accordance with a particular aspect of the present invention, an "up-reverse" pilot valve means having a pressure operator is connected in parallel with the reverse lock valve means. The operator is connected to the trim-up port of the source. In a trim-up mode, the "up-reverse" pilot valve means is therefore positively held open and provides a by-pass path around the reverse lock valve means which closes when in reverse gear. The valve means introduces a restriction in the flow path, thereby reducing the effective pressure applied to raise the trim and shock absorbing operator means to prevent full trim-up. When running in the reverse lock valve means is closed. The pump circuit is also positively held open to positively prevent operation of the pump and thereby preventing trim-up while running in reverse.

The apparatus also provides for automatic trailover at low speed impact movement of the lower unit by the maintaining of the return path essentially unrestricted in forward gear or neutral. However, the trim-up hydraulic side of the operator means is effectively sealed. Although the operator moves such as the expansion of a piston-cylinder unit to allow the movement of lower unit over the low impact load, hydraulic liquid is not drawn into the system on the trim-up side of the piston-cylinder unit. Consequently, after the device rides over the load, the lower unit automatically returns to the initial trim-set position, thus effecting a "memory" response. At high speed impact the flow system essentially is that described for slow impact. However, the return flow will not permit the complete free movement and consequently the cylinder pressure increases and at a selected point opens shock valves within the system and particularly within the piston assembly which absorbs the forces and prevents kicking or rapid movement of the lower unit. After high speed impact, a metered orifice and check valve means allows return to the original trim-set position as a result of the desirable memory feature.

The hydraulic supply system of the present invention as applied to a combined trim and shock absorbing cylinder unit therefore produces a highly accurate and positive control, permitting the lower unit to tilt or move upwardly under relatively safe conditions and automatically returning to the desired trim position while also permitting the high speed impact compensation essential to safe motor boating and the like. The trimming can be readily effected while under forward running conditions and to a limited degree in non-running reverse gear position. Further, the hydraulic supply system does not require any complicated control structures or the like and can be conveniently and economically manufactured while maintaining or while providing reliable operation over a long operating life.

FIG. 2 is a schematic flow diagram of a hydraulic system constructed in accordance with the teaching of the present invention for the outboard motor power trim assembly of FIG. 1;

Piston-cylinder units 10 are connected to a suitable pressurized hydraulic source which is conventionally a constant displacement reversible pump means 13 and reservoir 14 located within the boat, with an interconnecting valve and control means 15 also located within the boat and connecting the output of the pump means 13 to suitable connecting hydraulic hose to the units 10. As more fully disclosed and previously identified in the above application, the hose system preferably provides for connection through the transom bracket mounting bolts 15a to the lower ends of the cylinder units 10, which includes internal passageways to the opposite ends of the cylinder unit 10.

The present invention is particularly directed to an improved hydraulic supply and control system for proper directing of the pressurized fluid to and from the piston-cylinder units and a preferred embodiment of the present invention is schematically shown in the hydraulic and electric diagrams of FIGS. 2 and 3.

Referring particularly to FIG. 2, the pair of piston-cylinder units 10 are diagrammatically illustrated including similar cylinders 16 having a piston end connected in parallel to a trim-up line 17 and the piston rod side of the cylinders similarly connected to a trim-down line 18. Piston units 19 are mounted in each cylinder 16 and move upwardly and downwardly in response to pressure at lines 17 and 18, respectively. The respective lines 17-18 of course function as return or drain paths when not pressurized. The lines 17-18 are particularly connected through a novel valving system to the constant displacement reversible pump 13 as the source of pressurized fluid. The trim-up port 20 of pump 13 is coupled to the reservoir 14 through a relatively high pressure regulating valve 21, shown as a spring loaded check valve, and the trim-down side or port 22 is similarly connected through a relatively low pressure regulating valve 23. The trim-up pressure may, for example, be set to a maximum on the order of 31 psi while the down side may be limited to 1200 psi. In addition, free floating check valves 24 are connected between the opposite sides of the pump 13 and reservoir 14, with a filter 25 shown between the trim-down check valve 24 and the reservoir 14.

The pump trim-up port 20 is connected to the trim-up line 17 of the piston cylinder units 10 by a pilot operator pressure regulating valve unit 26, diagrammatically shown as a piston operated check valve assembly. The valve unit 26 is illustrated as including a valve housing 27 with check valve ball 28 movable into engagement with an upstream valve seat 29. Preferably a soft seat valve is used in place of the illustrated ball check valve. A spring 30 resiliently holds the ball 28 in engagement with the valve seat 29, and is set to open at a relatively low pressure on the order of 50 psi. The valve seat 29 includes an inlet passageway 31 connected to the trim-up line 20 which opens the valve to transmit pressure to the trim-up line 17. The valve unit 26 further includes a pressure responsive operator shown as a piston-cylinder type with a chamber 32 secured to the upstream side of the ball check valve housing 27 and with a piston or plunger 33 slidably mounted therein. A piston rod 34 extends into the valve inlet passageway 31 for selective engagement with the check ball 28. The pump port 20 is coupled to the operator chamber 32 to the piston rod side of the piston 33. Thus, when the pump 13 is operated to pressurize the trim-up port 20, piston 33 is withdrawn and transmits full pressure to and through valve 26. The units 10 are then powered to trim-up the outboard motor lower unit by forcing of the piston 19 outwardly of the piston cylinders 16. The fluid to the piston rod side of such units 10 is returned through trim-down line 18 which is returned to the reservoir 14 as follows.

The pilot valve means 37, which may also be a soft seat valve, is shown as a spring loaded check valve assembly having a pressure responsive operator similar to valve means 26 in the trim-up path to the piston cylinder units 10. Thus, valve means 37 includes a check ball valve 45 having an inlet port connected to line 18 and an outlet port 46 resiliently closed by a ball check 47. The pilot valve means 37 also includes a cylinder operator 48 having a central piston 49 operable to move the ball check 47 to open the valve means 37. The valve opening 46 is connected by a by-pass line 50 to the common connection between the reverse lock valve means and the down pilot pressure valve means 36. This then provides a restricted by-pass. The operator 49 has the piston side connected by a control signal line 51 to the trim-up port 20 of the pump 13 in the illustrated embodiment, in series with the valve means 26. Thus, with the pump 13 operating to pressurize the trim-up port 20, the pilot check valve means 37 is also pressurized and will positively hold the valve open and maintain the restricted flow path through orifice 46, in parallel with the closed reverse lock solenoid means 35.

When running in reverse gear, the thrust of the lower unit is applied in the direction to trim-up. However, the reverse lock solenoid valve means 35 is now positively closed. Trim-up by actuation of the pump 13 can occur with return flow occurring through valve means 37. Tilting up movement of the engine is prevented by the action of the pilot check valve means when the pump 13 is inactivated

Trim-down is affected by reverse running of the pump 13 to pressurize the trim-down port and line 20 with the following operation. The trim-down line 20 is connected to the "down" pilot pressure valve means 36 which is diagrammatically illustrated as a spool-type valve having a cylindrical valve chamber 52. An intermediate common port 53 is connected to the reverse lock valve means 35. The return port 54 for trim-up operation is connected to one end of the spool valve chamber 52 while a trim-down port 55 is connected directly to the opposite end and is also connected to pump line 22. A spool 56 is slidably mounted within the cylinder 52 with a spring 57 acting between the spool 56 and the trim-up port end to continuously bias the spool to close the trim-down port 55 and maintaining the unrestricted trim-up return flow.

When the pump 13 is operated in a reverse direction to pressurize the trim-down port 22 pressure builds within the corresponding end of chamber 52, causing the spool 56 to move against the force of the spring 57 and sequentially closing the common port connection to port 54 and then moving beyond such common port to open the connection to the trim-down port 55. The flow is from port 55 through valve 36 and then through the reverse lock valve means 35 and pilot valve means 37 in parallel to trim-down line 18, biasing the cylinder units 10 trim-down by moving of pistons 19 downwardly. This requires the liquid on the piston side of units 10 to flow out to line 17, which is in the direction to set the ball check 28 to close valve 26. The trim-down port 22 is also connected however via a coupling line 58 to the operator chamber 32 of valve means 26. Pressure in part 22 moves piston 33 and rod 34 to positively hold valve 26 open.

Thus, the trim-down line 18 to the piston-cylinder units 10 is pressurized and the piston-cylinder units 10 are actuated to move the pistons 19 and piston rods downwardly as shown in FIG. 2, to trim-down with the fluid to the opposite side of the pistons 19 returning to the low pressure side of the pump 13 via the trim-up line 17.

Trimming down in reverse gear will occur in the same manner. In the reverse gear, however, the reverse lock solenoid valve means 35 is closed. This valve is preferably a soft seat seal type valve such that as the pressure rises, limited reverse flow is premitted to the trim-down line 18. Thus, on the trim-down while in reverse gear, the output of pump 13 must increase sufficiently to move the "down" pilot pressure valve, the reverse lock valve pressure and the pressure necessary to move the trim cylinder unit against the reverse thrust. The "down" pilot pressure valve 36 is set to require a pressure in excess of 300 psi to insure the opening of the valve unit 26 prior to pressurizing of the trim-down line 18. The spool valve unit 36 when shifted to pressurize line 18 establishes an unrestricted flow and maintains full pump pressure in line 18. Normally, the total pressure must reach 300 to 600 psi in the reverse output and as previously noted, the pump is capable of producing 1200 psi.

As shown in FIG. 3, the reverse lock solenoid 38 of valve 35 is connected in series with a reverse lock switch means 58 which is coupled to the reverse gear unit 58a of the motor, the battery supply is connected to switch means 58 in parallel with the trim motor control. Thus, the pump is shown including a reversible D.C. motor 59 having forward and reverse windings connected to the battery supply in series with corresponding control switches 59a. The illustrated circuit is simplified for purposes of illustration. Thus, the system will normally provide various additional controls such as an up-limit tilt switch and the like.

In the forward gear or neutral position, the illustrated hydraulic system is such that the lower unit 8 may trail over an object or be manually lifted. Thus, with the boat moving forward and in forward gear or neutral, an impact load applied to the lower unit 8 will mechanically cause the pistons 19 and attached piston rods to move in the up-direction. The fluid to the piston rod side of the piston cylinder 16 is free to move through trim-down line 18, the normally open reverse lock valve means 35 and the free flow "down" pilot pressure valve means 36 to the reservoir 14.

However, as the pistons 19 move, fluid does not enter to the opposite side of the hydraulic system and the fluid is trapped within the up-side such that the pistons 19 position remains relatively constant. Thus, valve means 26 is pressure regulated by spring 30 which is selected to prevent the valve from opening as a result of the "trail-out" or shock absorbing movement of the piston units 19. After trailing over, the lower unit 8 drops and automatically causes the pistons 19 to return to the previous trim-set position.

The unit will also similarly function under a high speed impact with respect to normal flow. However, a high speed impact load tends to create a substantial flow, the system restricts such flows and the cylinder pressure increases. The piston units 19 of the combined trim and shock absorber unit 10 are specially formed as a two piece assembly, as more fully described with respect to FIGS. 4 and 5, to define a reservior 60 between a floating trim piston member 61 and a shock piston member 62 secured to the piston rod 63. The energy of the impact as seen by the shock rod 63, as it moves outwardly, is absorbed by the piston member 62 which includes a pair of shock valve units 64 and 65. The valved piston member 62 allows the shock forces to exist on the piston units 19 for a given length of time reacting to the force of the shock rod and resisting the rotation of motor. During the shock, hydraulic fluid is passed into the reservoir 60 via assembly 64. After the shock, the fluid is allowed to return through check valve assembly 65 in the opposite side of the piston. This allows the motor to return to its original trim position.

As shown in FIGS. 4 and 5, piston-cylinder units 10 are connected to receive and return hydraulic fluid to and from opposite sides of the piston unit 62. The lower end of the cylinder 10 is closed by a head 80 which threads thereon, while the upper end formed with an integral end wall 81 within which piston rod 62 is slidably mounted. The cylinder 10 is a double wall assembly including an inner cylinder liner or jacket 82 spaced inwardly of the cylinder 10 to define a transfer passageway 83 between opposite ends of the cylinder unit. The outer wall 10 is formed with a plurality of circumferentially spaced side wall protrusions 84 which are machined to abut the outer wall of liner 82 to accurately locate the liner and define passageways 83 therebetween. The outer end of liner 82 abuts a washer 84 adjacent the inner surface of end wall 81. Washer 84 has peripheral slots 86 defining passageways from transfer passageway 83 to the cylinder chamber and particularly to the rod side thereof. A bleed opening 87 in end wall 81 is closed by a cap screw 88.

The upper end of the cylinder unit 10 with the integral head wall 81 conjointly with the special ported lower head 80 thus minimizes the overall length of the cylinder unit 10 and creates a maximum operating or working stroke of piston unit 62 and rod 63. This is a particularly significant structure where the placement of combined power trim and shock absorbing means are to be placed within the mounted bracket assembly in order to establish a high satisfactory combined trim positioning and shock absorbing stroke of the units. This structure therefore provides a very compact assembly while maintaining reliable high powered positioning of the assembly. Further, the lower head construction permits a very convenient and protective connection of the hydraulic input/output lines. As disclosed in the previously identified application, the lower heads 80 of a pair of side-by-side units may be connected to a manifold unit 97 pivotally mounted on assembly 12 and connected to units 10 for pivoting therewith and having suitable conduits, not shown, connected to fittings 95 and 96.

Supply hoses or lines 17 and 18 each are similarly connected via hoses and bolts 15a to manifold 97 for conducting hydraulic liquid to and from the lower end of the piston cylinder units 12.