OP-755 Part 2 Pages 197-401 - Personal Page of GENE SLOVER

308
(1) The control pump relief valve adjusted too
low to provide enough pressure to operate
the hoist.
Install a pressure gauge in the inlet
flange of the control pump, and check
the pressure to be 160 Ibs. per square
inch. Adjust relief valve if necessary
as explained in paragraph 83.
(2) Control pump relief valve stuck open.
Removethe acorn nut and adjusting screw.
Reach into the opening and check the
valve to see if it is free from binding.
(3) The oil filter on the A-end clogged. The
pressure may seem to be correctly set at the
pump but the filter may prevent the flow of
oil to the control pump circuit.
Remove the filter cores from the A-end
filter assembly and clean.
(4) The control pump damaged.
Remove the control pump, dismantle and
check for worn or damaged parts.
(5) Restriction #44 is clogged.
Remove pipe plug 196826-11 from the top
of the valve block assembly and remove
the restriction plug for inspection.
(6) The by-pass valve 274283-3 in the valve block
assembly 274272 may be stuck in its vented
position.
Dismantle the valve block and check the
valve to be free from binding. (See
!!To Dismantle Valve Block!!.)
(c) Failure of main circuit. - If the pressure
does not build up to operate the hoist when
the control selector lever is positioned for
a "Servo Mechanical!! controlled cycle the trouble
will be in the main circuit, and will probably
be caused by one of the following reasons:-