overshot assembly brands

Overshots are a key component of wireline coring systems. To retrieve the core sample, the overshot is lowered into the hole on a wire cable until it comes in contact with the spearhead point on the head assembly. Positive latching lifting dogs securely attach, and the inner tube assembly is pulled from the hole to retrieve the core. V-lock Overshots Hole Products" V-lock overshots are safe, reliable, fast, and easy to use. The automatic safety feature is designed to reduce the chance of an accidental release. When the inner tube assembly is attached and lifted, the lifting dogs automatically retract into position. No extra manual steps are required to activate the safety feature, thus reducing the potential for human error. Standard Overshots Hole Products" standard overshots feature a manual safety lock pin. Once the core filled inner tube is hoisted above the top of the drill rods the safety lock pin can be inserted through the overshot head and under the spearhead point. This will allow the operator to hoist and remove the core sample from the inner tube.

In today’s drilling operations, safety is not an option; it is a critical component of every successful drilling project. We have developed our Excore EX II Safety overshot with both safety and performance in mind.

As a result, drillers are confident and have a peace of mind with one less process to worry about. This overshot simplifies the process and maximizes the speed of each over cycle resulting in increased productivity levels.

An OVERSHOT is attached to the end of a wireline and lowered into the outer tube. The Overshot then locks on to the Latch Head Assembly at the top of the core barrel.

The inner tube is then pulled to the surface with the core sample inside. Givens International offers an overshot for a spear point or quad latch head.

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Shop for overshot on Alibaba.com to find a variety for every season. Place small orders for individual use or large shipments to sell as a brand. Look for overshot that are designed for long-lasting comfort and trendy style. Each one pairs well with a wide range of other clothes and accessories to make versatile outfits for any occasion. Find different suppliers to help you get just the right price.

Most overshot have short sleeves that make them ideal for keeping cool in warmer weather. Some are designed to have a fashionable appearance, while others are made for athletic wear. Look for garments made of woven fabrics such as cotton when you need something comfortable. Fabrics such as spandex or bamboo allow for flexibility and stretchiness for a better fit.

Most manufacturers of overshot on Alibaba.com allow for a wide array of customization options. Order a shipment with just the right colors and sizes for your needs. Packaging and graphics can be made to order as well, ensuring your clothing will look just the way you want. Some suppliers offer sample shipments to try the product out before placing a full-sized order in the future.

Look for overshot on Alibaba.com to get as many as you need while keeping within your budget. A wide selection of fashionable and athletic versions are available. Whether you need them for yourself or your customers, overshot can be found with the features and styles to suit your tastes.

Since Boart Longyear introduced the Q™ Wireline system in 1966, retrieving the inner tube from the core barrel has been handled the same way: an overshot with lifting dogs (spring loaded hooked “fingers”) is lowered or pumped into the hole until it snaps over a pivoting spearhead mechanism affixed to the inner tube assembly. Once the head assembly has been removed from the hole, the driller uses the pivoting spearhead to position the head assembly on their workspace and squeezes the back of the lifting dogs to release.

Spearhead Handling: in up-hole applications underground, a driller is required to manually push the head assembly into the hole by the spearhead. Since it has a pointed end and pivots by design, it can be difficult to handle this operation comfortably.

Inner Tube Handling: When hoisting the inner tube assembly, elastic action of the wireline cable or accidental impact during handling can un-load cable tension and overcome spring loads which allows the hooked lifting dogs to accidentally release the spearhead. The surface ‘Ezy-Lock™’ overshot includes a twist-sleeve that locks onto the spearhead even without cable tension, whereas competing overshots require cable tension to maintain a lock.

Boart Longyear currently provides a secondary safety pin that clips through the overshot, passing just under the spearhead tip. This adds an extra layer of protection in case the lifting dogs are excessively worn or deformed. However, spearheads are loaded cyclically and often loaded ‘off-pivot’, which deforms the components over time, to the point of disassembly. While the more recent MKII™ version of the spearhead assembly is much more robust, in the case of spearhead failure, the head assembly will release from the overshot regardless of lifting dog or safety pin use or condition.

This patent-pending overshot leverages our previous experience with Roller Latch™ head assemblies to create a more reliable and longer lasting system that eliminates spearheads and lifting dogs entirely. The spearhead assembly is replaced by a one-piece socket receptacle (spearhead adapter) that accepts the overshot itself, which has rollers that latch into an internal groove in the spearhead adapter.

The increased toughness and hardness of the bearing quality latch rollers have a proven history of outlasting traditional pivoting latches for wear life. The new overshot will also feature the same Nitreg™-ONC surface treatment as Roller Latch head assemblies that drastically improves corrosion resistance (Nitreg is a trademark of Nitrex Inc.).

Safety pin integration in the new underground Quick Pump-In™ overshot now pulls double duty of both locking the overshot from accidentally releasing while hoisting, as well as holding the head assembly and overshot together in case of component failure due to excessive wear. Also, the socket and rollers are not affected by side loading and ‘off-pivot’ loading during tube handling outside the hole, eliminating gradual deformation or disassembly. The new surface overshot will also include a one-hand twist-lock sleeve to maintain a locked position while hoisting outside the hole, even with a loss of wireline cable tension.

It’s also easy to use.  Instead of pushing the backs of the lifting dogs together, the driller pushes the two halves of the assembly together, retracting the rollers and releasing the head assembly. This operation takes about the same amount of force as the current overshot, so drillers won’t miss a beat.

Additional benefits have been included[CA1]  apart from the elimination of the spearhead and lifting dogs. While the current design uses a solid pivot pin that is peened into place (making it difficult to re-build), the Roller Latch Overshot has no pins whatsoever. Everything is held in place by simple threaded connections for easy maintenance.

The Roller Latch Overshot features a brand new pump-in cable release system, originally conceptualized and prototyped by one of our expert underground drillers in Canada. A slotted sleeve and pumping seal assembly is placed over the wireline and pumped up to the overshot. The sleeve engages a quick-release mechanism and releases the wireline. This system has proven to be much more reliable, and may be the feature drillers are most thrilled to have going forward.  Reports of fewer broken wirelines have been received from several sites testing the pump-in cable release system.

Second, while Q/P Roller Latch head assemblies with built-in brake features have had great success in stopping runaway tubes and creating a safer drilling environment underground, they are perhaps “too” successful. Currently, when retrieving the head assembly from an inclined hole, pressure has to be applied to disengage the brake. Getting this pressure and procedure exactly right can be difficult, especially with hydrostatic pressure at depth.

To combat this and make Q/P Roller Latch easier to use while maintaining its safety features, a ‘brake release spring’ was created. This spring assembles quickly inside of the spearhead adapter on the head assembly. While tripping on its own, the head assembly brake works normally, but when the overshot latches into it this spring is compressed, disengaging the brake. This feature has also been received very positively by drillers in the field.

A surface-style overshot is also in development in B/N/H sizes. In addition to many of the features outlined in this article, the aim is to add more innovations, including:

• An improved lock sleeve to disable accidental head assembly release and stop drillers from accidentally sending the overshot down the hole while locked.

The new overshot applies our experience with Roller Latch head assemblies to create a system that eliminates spearheads and lifting dogs entirely. The spearhead is replaced by a socket adapter that accepts the overshot itself. Rollers securely latch into an internal groove in the adapter.

The new overshot is designed for self-flushing and — if need be — easy cleaning by flushing through the porting provided. The wedge has three large flats to ensure no debris build up. Using past experience, we have been able to improve the function of the landing indication system for better productivity with your overshot. With a brand new pump-in cable release system, the Roller Latch will eliminate shear pins and increase the reliability of wireline recovery.

SPS Mining Supplies Ltd. offers spare and complete overshot products in BC and the Yukon for use in coring. From our location in Smithers, we can have tools delivered straight to your jobsite the very same day. When your productivity and profitability matter, you can count on SPS Mining Supplies Ltd. — give us a call today! We carry parts from brands such as: