Navistar WorkStar Series, Operator'S Manual

Page: 175 / 258

Operation
allow it to be moved forward or backward and re-lock it once
the desired position is attained.
To unlock the fifth wheel, press the top portion of the
switch in. The switch indicator will illuminate steadily
when the fifth wheel is unlocked.
NOTE: The fifth wheel cannot be unlocked above a
preset speed (normally 2 mph). Attempting to unlock
the fifth wheel at any higher speed will cause the switch
indicator to flash slowly (once per second). The fifth wheel lock
automatically engages if it has been unlocked and the vehicle
speed exceeds the preset value.
To lock the fifth wheel once the desired position is reached, press
the lower portion of the switch. The switch indicator will turn off
when the fifth wheel is locked.
NOTE: A fast flashing (twice per second) switch indicator
signifies a problem in the fifth wheel lock system.
Hook-Up
1. Fifth wheel jaws must be opened fully.
2. Tilt fifth wheel back to prevent body damage when
tractor is backed under trailer.
3. Block trailer wheels and be sure trailer spring brakes are
adjusted and applied. Never chase a trailer.
4. Make sure brake hoses and light cords are clear of the
fifth wheel.
5. Back tractor squarely under trailer, engaging fifth wheel
jaws on trailer kingpin. Always back slowly, making sure
trailer is neither too high nor too low. Avoid backing
under trailer from an angle.
6. Connect service and parking brake hoses and trailer
light connector.
Refer to the Warning located in the
Tractor-Trailer Connections information. Use a
three-point stance when connecting and disconnecting
trailer.
7. Inspect fifth-wheel jaws to be sure they have closed on
trailer king pin and the trailer plate is resting securely on
the fifth wheel.
8. Be sure the coupler release lever is in the locked
position.
9. Charge trailer brake system. Set trailer brakes, either
with the hand valve or tractor protection valve.
Pull
against trailer for an additional check of hook-up. Do not
pull hard enough to damage or strain the equipment.
10. Set tractor parking brakes and fully raise trailer landing
gear. Refer to Brakes segment of this section for
Operation of Parking Brakes and Trailer Brakes.
11. Check operation of all trailer lights and correct faulty
lights.
Un-Hook
1. Try to keep tractor and trailer in straight line.
2. Apply tractor and trailer parking brakes.
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