2.2 Basic Troubleshooting - Mechanical
Problem
Possible Cause
Remedy
Front only or rear
only stabilizers
operate.
Supply hose leaking
Pilot-operated check valve
defective
Check hose for pressure.
Replace defective
pilot-operated check valve.
Upper section of
A-frame will not
raise
A-frame flow control valve
defective
Breather plug in cylinder
obstructed
Replace valve.
Remove and clean breather
plug.
A-frame will not
lower
Front support frame unlock
solenoid defective
Unlock pawl loose on shaft
Flow control valve defective
Refer to Hydraulic System
troubleshooting.
Check pawls for security;
replace roll pins if missing or
defective.
Replace flow control valve.
Adjustable section
will not extend;
stabilizers will
extend
Adjustable section overloaded
Foreign matter between
channels and main support
wheels
Adjust load.
Clean channels and wheels.
Lubricate channels with
all-purpose grease.
Adjustable section
will not lower
Objects left on stair treads
jammed between intermediate
platform and adjustable
platform
Stair unlock solenoid defective
Raise section and remove
objects; check for damage.
Refer to Electrical System
troubleshooting.
Adjustable section
lowers too slowly
System relief valve set too low
Foreign matter between
channels and main support
wheels
Adjust relief valve to 1,200
psi (84.37 kgps cm).
Clean channels and wheels.
Lubricate channels with
all-purpose grease.
SEPTEMBER 30, 2008
CHAPTER 2 MAINTENANCE
PAGE 2
2 TROUBLE SHOOTING
Truck Mounted Passenger Stair TMPS-200
Manual No. 307559
