We recommend field service repairs be limited to replacement of packing, bushings and wipers with initial setting of head nuts as described in this section.

After repair, a damp to light film of oil may be apparent on the plunger. A small accumulation of oil may be noticed on the plunger at the adjustable head nut after many cycles. This should not be mistaken for packing leakage.

If a cylinder cannot be corrected by minor field repair, we recommend that the cylinder be returned to Custom Hoists, or a factory qualified service dealer.

If necessary to disassemble a cylinder due to a damaged part such as a plunger, the cylinder should be completely disassembled and all parts inspected. When requesting information or ordering parts, refer to the cylinder and serial numbers located at the base end of the cylinder. A Major Repair Kit should be installed when rebuilding the cylinder.

Figure 2 shows a typical sequence of
disassembling the cylinder plungers in steps.

Figure 1

*Packing Set

Back to Top

Step 2 - Set Screws
All head nuts are secured to the plunger by a set screw. Under the set screw is a nylon slug to protect the plunger threads. To remove the head nut, the set screw must be loosened using an allen wrench.
(Refer to Figure 3)

Step 3 - Head Nuts
After the set screws have been loosened, tap head nut gently around its circumference and unscrew the head nut with a chain wrench, or an equivalent tool. Do not use a chisel, punch or weld any studs to the head nut to remove. (Refer to Figure 4) 

Step 4 - Bushings
Using a small chisel, tap gently upward with a mallet uniformly around the circumference of the bushing. (Refer to Figure 5) 

Step 5 - Packing, Wave Spring, Lower Bushing 
To remove packing, wave spring and lower bushing, pull the plunger up about one foot. Add tape to a clean area as shown in Figure 6. Push the plunger down past the packing then pull the plunger up. The internal parts will stick to the tape and be pulled out of the plunger.
Repeat as needed.

Step 6 - Retainer Rings
The retaining ring has a small hole at each end. Insert a pointed screwdriver to move the hole out into the I.D. Place a steel shim behind the retainer. Using the Custom Hoists' retainer ring tool, insert the points into the retainer and close the retainer against the tube. Pull the tube to remove the retainer and plunger stop. (Refer to Figure 7)

Reassembly of Cylinder
All bores in the packing area and plunger outside diameters must be free of tool marks and scratches. Polish with a fine paper, crocus cloth or a Scotch Brite pad. All parts should be clean and free of any contamination. A complete major repair kit is recommended. Drop all plungers into the body in the vertical position, as shown in Fig. 1. Assemble the remaining parts in the reverse sequence as listed in Fig. 2. The packing should be presoaked in oil before installing (do not use a detergent oil). Note, Fig. 2 for the direction of the packing. Using a tool similar to Fig. 9, seat each lip individually, making sure packing is nestled uniformly. After setting the head nuts (Step 7, Fig. 8), make sure there is a nylon slug under the set screw before securing the head nut to the plunger. After installing the cylinder in the unit, open the bleeder screw and extend the cylinder to bleed the air. More than one extension may be needed to assure all the air is removed and cylinder operates smoothly.

 Step 7 - Setting Head Nuts
Remove the small slug located opposite the set screw. Using a 5/32" hex wrench (as shown in Figure 8), tighten the headnut down until the hex wrench bottoms out on the top of the plunger. Remove the hex wrench and replace the slug. Install the set screw using a nylon slug to protect the threads.

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8