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Remove the jaw pins by driving them out from the bottom. Then, remove the jaws and jaw pins
and clean all the parts carefully.
Put the jaws, pins, fork, and linkage and linkage bushings on a bench. Inspect all components
carefully. Look for cracks and wear. The king pin hole on the jaws (when closed) is 2.00 inches
(plus +1/32 minus-zero) when new. Wear of greater than 1/8 inch from these specifications calls
for replacement of the jaws. The wear pattern will be oval shaped with more wear found along the
length that the width of the jaws. Replace jaw pins if excessive wear is found. The pins should be
1 1/8 inch diameter.
If the fork is cracked or badly worn it should be replaced. Inspect the linkage and linkage
bushing. Replace if worn.
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Inspect the wear plate on the 5
wheel. This is the steel plate that the jaws rest on. If the plate is
worn thin, it should be replaced. (Instructions for this repair are included with a new wear plate.)
Re-install the jaws and the jaw pins with the 3 inch counterbored surface facing the ground. Be
sure that the top of the jaw pins are slightly below the top surface of the 5th wheel plate. If the
pins stick out above the 5th wheel plate, you must counterbore the jaw pin holes. (If a
counterbore is needed, use a 1 5/16 inch counterbore.)
Place the fork into the assembly and see if it slides easily into the locked position. If you are
inspecting a locking assembly that was not operating properly and you are not replacing with new
parts, you should grind the fork where any marks are present. Make sure that the fork will slide
easily into the locked position. A new fork will normally need some grinding to fit properly.
Install in this order: fork, flat washer, steel bushing, linkage, flat washer, and Nylock nut. Loosely
install the other end of the linkage in the air chamber clevis. Install the pivot bolt and nut. Tighten
the Nylock pivot nut fully, and then back the nut off about 3/4 of a turn so that the linkage can
pivot freely on the bolt.
Tighten the fork Nylock nut, and then back it off so that the tat washer under it can turn freely.
Adjust the clevis on the air chamber so that you must pull the air chamber shaft out about 1/8 inch
to put the clevis pin through the linkage and clevis. Use a 5/8 inch open end wrench as a lever to
force the clevis out so that the pin will go through. When the pin goes through, use a new cotter
pin to secure it.
IT IS IMPORTANT THAT SPRING PRESSURE FROM THE AIR CHAMBER WILL
ALWAYS BE APPLIED TO THE LINKAGE. BE SURE THAT YOU PULL OUT THE
CLEVIS THE CORRECT AMOUNT. BE SURE THAT THERE IS NO SLOPPINESS IN
THESE PARTS!
DO NOT TIGHTEN THE NUTS TOO TIGHTLY OR THE FIFTH WHEEL WILL NOT LOCK!
Hook up the spring on one jaw to the hook or anchor bolt on the 5th wheel plate. Re-install the air
cylinder. Hook up all air lines. Inspect your work at this point. Start the tractor engine and build
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up tractor air pressure to 100 psi, Push the jaw release button in the cab. This prepares the 5
wheel for service. Be sure that the jaws open fully.
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Test the 5
wheel under a loaded trailer. Repeat the entire locking procedure. If the fork does not
go in all the way, hit the fork rod, remove the fork and grind the fork where it is binding. DO
NOT GRIND THE JAWS, only the fork.
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Warren Elevating 5
Wheel
39
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