Lull 944E-42 Service Manual User Manual download pdf (Page 494)

100

101

Hydraulic System

8.242

Model 644E-42/944E-42 Rev. 6/04

Note: It may be necessary to apply heat to break the

bond of the sealant between the locknut (11) and the

rod (3) before the piston (5) can be removed. Some

parts of cylinders are sealed with a special organic

sealant and locking compound.

Before attempting to disassemble these parts, remove

any accessible seals from the area of the bonded joint.

Wipe off any hydraulic oil and heat the joint uniformly to

break the bond. A temperature of 300-400° F (149-204° C)

will destroy the bond. Avoid overheating or the parts may

become distorted or damaged. Apply sufficient torque or

pressure for removal while the parts are still hot.

Breakdown of sealant will leave a white, powdery residue

on threads and parts. Clean the residue away with a soft

brass wire brush prior to reassembly, and wipe with

Loctite “T” cleaner before reinstallation.

10. Remove the piston (5), rod spacer (12) and head

gland (4) from the rod (3).

11. Remove the o-ring (13) from the head gland (4).

12. From within the head gland (4), remove the precision

wear band (14), the DZR seal (15) and the sealed

outside diameter heavy-duty rod wiper (16).

13. From within the piston (5), remove the small o-ring

(17).

c. Transfer Carriage Cylinder Cleaning

1. Remove all hydraulic fluid, dirt and debris from the

inner surface of the cylinder.

2. Discard all seals, back-up rings and o-rings. Replace

with new items from a complete seal kit (18) to help

ensure proper cylinder function.

3. Clean all metal parts with an approved cleaning

solvent such as trichlorethylene. Carefully clean

cavities, grooves, threads, etc.

d. Transfer Carriage Cylinder Inspection and Repair

1. Inspect all parts for wear and damage. If inner

surfaces of the cylinder (1) do not display an ultra-

smooth, polished finish, or are damaged in any way,

replace the damaged part. Often, dirty hydraulic fluid

causes failure of internal seals and damage to the

polished surfaces within the component.

2. Inspect the inside of the tube (2) for scoring and

other damage. If the tube is damaged, replace it with

a new tube.

3. Remove small scratches on the rod or inside of the

tube with very fine grit emery cloth. Use the emery

cloth in a rotary motion to polish out small

imperfections in the metal and blend scratch(es) into

the surrounding surface.

4. Clean the parts with trichlorethylene after repair.

5. Check that the rod (3) is straight. If the rod is bent,

install a new rod.

e. Transfer Carriage Cylinder Assembly

Note: Follow Section 8.14.3, “General Cylinder

Assembly Instructions.”

1. Install the DZR seal (15) into the head gland (4).

2. Install the precision wearband (14) into the head

gland (4).

3. Install the heavy-duty rod wiper (16) with the raised

portion of the lip seal (19) oriented toward the rod

eyelet. The wiper lip (19) should be toward the outer

end of the head gland and the seal lips toward the

inner end of the head gland. Use tools that will not

damage the seals.

4. Install new oiled o-ring (13), back-up ring (7) and

oiled o-ring (6) onto the head gland (4). If the

back-up ring is not flat on both sides, the side with

the arc must be toward the o-ring.

5. Install the head gland (4) onto the rod (3). If

necessary, use a soft hammer to drive the head

gland onto the rod.

6. Install the new small oiled o-ring (17) into the

piston (5).

7. Install the capped T-seal (10) onto the piston (5).

Note: The T-seal actually consists of four components; a

wide, flexible inner band, the flexible T-seal band itself,

and two supportive split caps that mount on either side of

the “T” seal band.

8. Install the two precision wearbands (9) onto the

piston (5).

9. Place the rod spacer (12) onto the rod (3).

10. Install the piston (5) onto the rod (3).

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Lull 944E-42 Service Manual User Manual Page 494

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