THIEMAN LRST-40, Руководство пользователя и список запчастей

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3. Problem - Liftgate will not lower with the pump motor running
Cause
a . Defective lowering
solenoid coil or valve
b . Clogged or defective
hydraulic lines, fittings or
flow controls
22 .
2. Problem - (continued)
Cause
h . Lift cylinders are
bypassing, liftgate is
drifting down
i . Broken hydraulic line
j . Clogged or disconnected
suction line
k . Defective pump
Correction
If the liftgate will not raise with a load on the platform but empty is raising
slowly or only partially, one or both of the cylinders may be bypassing . To check
for bypassing cylinders do the following . Lower the gate to the ground to relieve
all pressure from the cylinders . Disconnect both cylinders from the liftarm .
Press the "RAISE" switch until both cylinders are fully retracted . Disconnect
the low pressure hoses from the power unit at the T-fitting at the C2 port at the
pump . Plug the newly opened end(s) of the T-fitting on the pump . Put the loose
ends of the disconnected hoses in a container to catch any oil, which comes
out during this test . Press the "RAISE" switch for 15 to 20 seconds and watch
for a steady stream of fluid coming out of one of the disconnected hose ends
into the container . If no steady stream of oil is present reconnect all hoses and
press the "LOWER" switch until both cylinders are fully extended . Disconnect
the high pressure hoses from the power unit at the T-fitting at the C1 port at the
pump . Plug the newly opened end(s) of the T-fitting on the pump . Put the loose
ends of the disconnected hoses in a container to catch any oil, which comes
out during this test . Press the "LOWER" switch for 15 to 20 seconds and watch
for a steady stream of fluid coming out of one of the disconnected hose ends
into the container . Replace or rebuild any cylinder with fluid coming out of its
disconnected hose end, as this indicates fluid is bypassing the piston seals on
the cylinder . Reconnect rebuilt or replaced cylinders and hoses as before .
Broken or punctured hydraulic lines and fittings must be replaced with care to
avoid iniury from high pressure oil streams .
With the liftgate at the ground, disconnect the power unit and remove the
reservoir . Check to see if the suction tube is clogged or has fallen out of the
pump base . Clean the screen or reattach the suction tube as required .
If all else fails replace the power unit, it may be defective . If the liftgate is older,
the pump may be worn out and unable to pump fluid at pressure with the
correct flow rate .
Correction
With the "DOWN" switch engaged check for voltage on the red wire at the
switch . If no voltage is present replace the switch . If voltage is present, with
the "DOWN" switch engaged, check for voltage at the red wire on the lower
solenoid valve coil terminal . If no voltage is present, the red wire from the
"DOWN" switch is loose or broken and needs replaced . Check for proper
ground at the purple wire on the lowering solenoid coil . Repair or replace ground
as required . If there is voltage (minimum of 9 .5 volts) and proper ground at the
lowering coil, and the valve is not opening to allow the gate to lower, either the
lower coil is bad or the entire lower coil/valve assembly is bad . To check to see
if the coil is defective, remove the red and purple wires from the spade terminals
on the lower coil and check the resistance between these spade terminals (3 .6 -
4 .4 Ohm acceptable) . Note: Low resistance can cause the 20 fuse to blow (see
Problem 1, part b) and high resistance will lower the coils magnetic force and
may not shift the valve . If proper resistance does not exist, replace the defective
coil, otherwise replace the defective lower coil/valve assembly
Remove any obstruction in the hoses, fittings or flow controls or replace any
hose, fitting or flow control, which does not allow fluid to flow through freely .