Use the following tools to service the cylinder:
MEL1074 – O-ring Seal Hook
Spanner Wrench
MEL1396 – Seal Installation Tool
MEL1033 – Rod Seal Installation Tool
Piston Ring Compressor
Wash the cylinder parts in solvent and air dry them.
Inspect the cylinder parts for nicks, scratches or other damage. Replace any damaged parts.
Always install new O-rings and seals during assembly.
Lubricate all O-rings and seals with hydraulic oil during installation.
Hold the hydraulic cylinder over a drain pan and move the rod in and out slowly to remove the fluid from the cylinder.
Put the base end of the cylinder in a vise.
Use a spanner wrench to loosen the head (Item 1) [Figure 20-22-5].
Assembly: Tighten the head with a spanner wrench until the head is seated all of the way into the cylinder (Item 2) [Figure 20-22-5].
Remove the head and rod assembly from the cylinder [Figure 20-22-6]. Put the rod end in a vise.
Remove the nut (Item 1), piston (Item 2), spacer (Item 3) and head (Item 4) [Figure 20-22-6] from the rod.
Assembly: Grease the piston where the nut contacts the piston. do not get grease on the threads. Install the new nut (Item 1) [Figure 20-22-6].
Assembly: Tighten the nut to 90 ft.-lb. (122 Nโขm) torque.
Remove the O-ring (Item 1), and seal (Item 2) from the piston (Item 3) [Figure 20-22-7].
NOTE: The piston center hole (Item 4) [Figure 20-22-7] has a bevel on one end. The bevel goes toward the rod when assembling.
Assembly: Install the new seal on the tool and slowly stretch it until it fits the piston [Figure 20-22-8]. Allow the seal to stretch for 30 seconds before installing it on the piston.
Once the seal is installed on the piston, a piston ring compressor can be used on the piston for 3 minutes to compress the seal into place.
Remove the two O-rings (Item 1) and the back-up washer (Item 2) [Figure 20-22-9] from the cylinder head.
Remove the wiper seal (Item 1) [Figure 20-22-10] from the cylinder head.
Install the wiper seal, with the wiper side of the seal (Item 1), toward the outside of the head (Item 2) [Figure 20-22-11].
Remove the rod seal (Item 1) [Figure 20-22-12] from the cylinder head.
Assembly: Install the rod seal on the rod seal tool [Figure 20-22-13].
NOTE: During installation the spring side of the seal (Item 1) [Figure 20-22-13] must be installed toward the inside of the cylinder.
Assembly: Install the rod seal in the head. Rotate the handles to collapse the rod seal [Figure 20-22-14].
Reverse the disassembly procedure to assemble the Bob-Tach cylinder.
