VALVE GP-CONTROL 3789365 - Caterpillar

Hydraulic accumulator contains gas and oil under high pressure. Improper removal or repair procedures could cause severe injury. To remove or repair, instructions in the service manual must be followed. Special equipment is required for testing and charging.
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products.Dispose of all fluids according to local regulations and mandates.
Illustration 1 g01048310
Illustration 2 g01048381Note: Make sure that the work area is free of dirt and debris. Foreign material that is trapped in the shell during assembly may cause damage to the bladder.
Place shell (5) in a horizontal position. Spray or pour clean oil into shell (5) in order to form a pool of oil along the full length of shell (5). The pool of oil in the bottom of shell (5) should be approximately 25 mm (1 inch) deep.
Roll shell (5) over several times in order to completely coat the inside of shell (5) with a layer of oil. Note: Do not roll the shell after the bladder has been installed in order to prevent twisting of the empty bladder.
Illustration 3 g01048392
Illustration 4 g01048401
Lay bladder (6) flat on the work surface. Use a lint free cloth to wipe hydraulic oil on the surface of bladder (6). Make sure that the entire surface of bladder (6) is covered with oil.
Illustration 5 g01048407
Press all residual air out of bladder (6).
Illustration 6 g01048410
Illustration 7 g01048416
Illustration 8 g01048418Note: Installation of the bladder will require one person at each end of the shell.
Place locknut (3) over the pull rod with the male threads in the direction of the handle on the pull rod. Note: If there is a Scrader valve core in the stem of the new bladder, remove the valve, and discard the valve. Accumulators that are built with M28 block (1) will give false pressure reading if the Scrader valve is installed.
Push the pull rod with a male Scrader to female M16x2 adapter through the small bore of shell (5) and thread the pull rod to the stem on the bladder.
Fold bladder (6) to a quarter of the bladder's original width. Pull bladder (6) into shell (5) from one end and push bladder (6) into shell (5) from the other end. Make sure that bladder (6) is not twisted when bladder (6) is inserted into shell (5).
Use the pull rod to pull the stem out of the top of shell (5). Once the stem is through the opening on shell (5), attach locknut (3) in order to prevent bladder (6) from slipping back into shell (5). Unscrew pull rod from the stem on bladder (6). Apply a liberal amount of hydraulic oil over bladder (6).
Insert fitting (8) into shell (5). Make sure that bladder (6) is fully extended within shell (5).
Fold