Figure 2-16. Shear-type fitting.

retract the rod. The head end line directs oil to the

nut. Tighten the nut an additional 1 turns. It is

head end of the cylinder to extend the rod.

not necessary to tighten the nut all the way down.

Figure 2-18. Hydraulic cylinder rod and head ends.

(b) Removal. The hydraulic system need not

be drained to remove any or all cylinders. Only the

oil in the lines between the cylinder and its control

v a l v e will be lost. However, the control lever must

remain in HOLD position or oil can drain from the

t a n k in some instances.

Figure 2-16. Shear-type fitting.

(c) Disassembly and assembly. R e m o v e a n d

(6)

Hydraulic

valves.

i n s t a l l the bolts securing the cylinder head to the

(a) E x a m i n e a l l v a l v e s , v a l v e b o r e s a n d

c y l i n d e r with the piston rod fully extended.

valve

seats for nicks, burrs and/or scratches.

(d) Cylinder head seals. T h e r u b b e r O - r i n g

( R o u g h spots may be removed with a crocus cloth

s e a l (1, fig. 2-19) and the backup ring (2) which

form the seal between the head (3) and cylinder

o r fine emery cloth). All valves which operate in

bores must slide freely in their bores. Be certain all

bore (4) are all assembled as illustrated. Note that

the toe or lip of all wiper seals (3, fig. 2-20) on all

p a s s a g e s are clean and open.

cylinders faces away from the cylinder head.

(b) O n c o n t r o l v a l v e s p o o l s h a v i n g b o l t -

r e t a i n e d centering or return springs (fig. 2-17) the

b o l t S hould be removed while the valve spool is in

t h e valve body. This procedure will prevent spool

d i s t o r t i o n and possible damage to the spool lands.

Figure 2-19. Cylinder head seals.

Figure 2-17. Removing bolt-retained spring.

(c) When installing shims to adjust pressure

settings, a l w a y s p l a c e t h e t h i c k s h i m o r s p a c e r

against the spring.

(7) Cylinders.

( a ) Rod end and head end. T h e " r o d e n d "

(1, fig. 2-18) of a cylinder is that end that has the

r o d extending. The "head end" (2, fig. 2-18) is the

o t h e r end of the cylinder-the blind end. The rod

end line directs oil to the rod end of the cylinder to