f. Reassembly. Refer to figure 3-131 and
hex socket setscrew in packing nut. With a spanner
r e a s s e m b l e hydraulic steering cylinder as described
wrench loosen and unscrew packing nut.
(3) All internal parts can now be taken out cm
the piston rod.
(1) P a c k i n g d r a g t e s t .
( 4 ) Hold rod end with pin through the eye to
(a) With cylinder horizontal, fill rod end of
p r e v e n t turning. Protect rod from damage. Remove
t h e cylinder with oil.
nut on piston end, slide parts off removing O-rings.
(b) Open head end part of the piston to the
( 5 ) Thoroughly wash all parts in solvent (Fed
P-D-680) and wipe or blow dry.
(c) W i t h r o d e n d u n d e r n o l o a d e x c e p t
(6) Install new back up rings and O-rings with
n o r m a l seal and wiper drag, pressurize the rod end
a minimum amount of stretching. Thoroughly
of the cylinder and record the maximum pressure
l u b r i c a t e all seals and packing with hydraulic oil.
reached before piston moves.
(7) Reinstall bushing into retainer and slide
(d) Repeat the above for head end of the
packing nut and assembled retainer onto piston
(e) The piston may be operated as necessary
(8) Install new packing and rider on piston
for wear in.
h a l f and slide on rod, slide O-ring into place and
(f) Piston rod will extent with maximum of
lubricate. Install washer, slide next O-ring into
15 PSI on piston. Piston rod will retract with
maximum of 25 PSI on rod side of piston.
( 9 ) Check cylinder bore to be sure it is clean
(2) P i s t o n L e a k a g e T e s t .
and free of any contamination.
(a) Fill cylinder with oil. Seal rod end and
(10) Use a length of brass shim stock to guide
load the head end of the piston to not less than
packing over threads. Apply another coat of
2000 PSI and hold this pressure for 15 minutes.
lubricant to all exposed seals and carefully insert
(b) Measure and record the travel of the
a s s e m b l y into shell. Push retainer into position and
piston during the 15 minutes.
tighten packing nut.
(c) Repeat procedure for rod end of
(11) Tighten setscrew firmly in place and
reinstall cylinders in truck.
( 1 2 ) Actuate hydraulic system, remove blocks
(d) Maximum piston rod drift not to exceed
a n d cycle through all functions to purge air from
1 inch per hour.
h. Adjustment. The steering cylinders must be
adjusted so each steering cylinder has an equal
amount of travel of the piston rods. The tie rods
Internal loos of pressure in the cylinder can be caused
must be adjusted to no toe in or toe out. Retract the
by a damaged O-ring between the piston half and rod
or the piston packing.
steering cylinder rod shaft. Mark (with tape) the
rod shaft against the face of the cylinder. Fully
Cylinders having the spherical bearing in the ends
extend the cylinder rod shaft and measure this
have a press fit but are also staked to prevent working
d i s t a n c e from. the face of the cylinder to the mark
m a d e with the rod retracted. Mark ½ this distance
d. Disassembly. Refer to figure 3-131 and
(with tape outside the ½ mark). Retract the
d i s a s s e m b l e h hydraulic steering cylinders.
c y l i n d e r rod to ½ the stroke (or edge of tape). The
w h e e l s must be in line. Screw on the cylinder rod
( 1 ) Inspect cylinder rod for nicks and damage.
e n d until the cylinder rod end lock pin can be in-
Damaged rods will shorten packing life.
serted in the lock pin hole. Torque the rod end
(2) Inspect shell for cracks and damage.
locking bolt to 40 ft. lbs. Adjust other steering
(3) Inspect piston for nicks and scratches.
cylinders in a similar manner.
(4) Remove nicks and scratches with crocus
i . Installation. Refer to figure 3-130 and install
hydraulic steering cylinder.
(5) Replace a defective part.