SUB-SECTION 5B
BOOM HOIST CYLINDERS
BOOM HOIST CYLINDER (38U92)
2. The sirvon piston ring seal should not be removed from
the piston unless a new ring must be installed, since
DISASSEMBLY. To disassemble the boom hoist cylinders,
removing the seal will permanently damage it. To replace
proceed as follows (see Figure 5B-2):
the sirvon piston seal, proceed as follows:
1. Remove screw (1) and washer to unlock the thread ring.
A. Remove the grey iron piston ring closest to the sirvon
Remove two screws (2). Insert a spanner wrench into the
piston seal groove.
screw holes in the thread ring, and unscrew the thread ring.
B. Warm the sirvon piston seal in either hot water or oil.
2. Pull the rod, thread ring, head gland, and piston out of
Install one side of the seal in its groove and carefully
the cylinder.
walk the other side into the groove.
NOTE
It may be necessary to bump the piston against the
When installing the sirvon piston seal, do not allow it
head assembly repeatly to force the head gland out of
to become twisted in the piston groove.
the cylinder bore.
REASSEMBLY. To reassemble the cylinder, proceed as
3. Remove the cotter pin at the piston end of the rod and
follows:
remove the piston nut. The piston, head gland, and thread
ring can now be removed.
1. Install the thread ring, head gland, piston, and piston
nut on the rod. Be certain that the cotter pin is installed
INSPECTION AND REPAIR. After the cylinder has been
properly in the end of the rod.
disassembled, clean all the cylinder components in a suit-
able commercial cleaning solvent, and then lay the parts on
2. Oil or grease the inside of the cylinder bore and piston
a clean workbench for inspection. Particular attention
thoroughly. Then carefully position the piston in the
should be paid to the following items when inspecting the
mouth of the cylinder, end rock the rod slightly to com-
cylinder components:
press the piston rings es they enter the cylinder bore. Slide
the head gland into the cylinder bore.
1. Carefully inspect all seals and components for damage or
NOTE
excessive wear. and replace as required. The grey iron
piston rings tend to wear or "break-in" to the mating cylin-
If the head gland has difficulty sliding into the cylin-
der bore surface. These piston rings should not be replaced
der bore, a pair of bar clamps should be used to apply
unless they have been seriously damaged.
a steady pressure to the herd gland. which will cause
2. The sirvon piston ring seal should not be removed from
the seals to compress and enter the bore.
the piston unless a new ring must be installed, since re-
moving the seal will permanently damage it. To replace the
3. Note the location of the two tapped holes in the head
sirvon piston seal, proceed as follows:
gland and mark these locations on the outside of the cylin-
der. Screw the thread ring into the cylinder bore until it is
A. Remove the gray iron piston ring closest to the sirvon
flush with the end of the cylinder.
piston seal groove.
Then turn the thread ring until the two countersunk holes
B. Warm the sirvon piston seal in either hot water or oil.
are aligned with the holes in the head gland. Install the two
Install one side of the seal in its qroove and carefuIly
countersunk head screws, and tighten both screws evenly
walk the other side into the goove.
until both screws are tight.
4. Install screw (1) with a washer and tighten it snugly to
lock the thread ring.
5. After the cylinder is reinstalled on the machine, cycle
When installing the sirvon piston seal, do not allow it
the cylinder slowly a full stroke in both directions repeatly
to become twisted in the piston groove.
to purge the trapped air from the cylinder.
REASSEMBLY. To reassemble the cylinder, proceed as
follows:
NOTE
1. Install the thread ring, head gland, piston, and piston
nut on the rod. Be certain that the cotter pin is installed
When air is present in the cylinders, jerky and/or
properly in the end of the rod.
irratic operation of the cylinders can be expected.
5B-2
