Hyd-Mech H-40, Operation And Maintenance Manual

Page: 38 / 95

Pg 3.7
H40
PROBLEM
15. Head still will not rise or
fall, or any individual function
will not respond to its manual
control switch.
16. Head will not descend.
17. Head descends when Feed
Rate Valve pointer is set to "0"
on the scale and Feed Force
Limit gauge is more than 150
psi.
PROBABLE CAUSE
15a. Observe pilot light(s) on
relevant valve. If pilot light
related to inoperative function
fails to light, problem is
electrical.
15b. If pilot light related to
inoperative function does light,
problem may still be the coil
(see 15a. solution). If problem
remains it probably results
from dirt in the valve spool.
16a. Feed Rate Valve is fully
closed - pointer is set on "0"
or close to "0" in/min.
16b. Feed Force Limit is set
toolow.
16c. Pointer is not adjusted.
17a. Pointer of Feed Rate
Valve is stopped by stop bolt
but not fully closing the valve.
SOLUTION
15a. In case of head function
check operation of related limit
switches. Limit switch levers should
operate freely and emit an audible click
on both depress and release. If not
replace the switch nose. Look for cause
of switch damage (ie debris or
maladjustment of switch actuator). To
check the switch unit itself, remove the
switch lid and wire together the two
terminals closest to the wiring port. If
function now responds to manual
switch replace internal limit switch unit.
If function still does not respond then...
Open panel door to gain access to
valves. Remove coil retaining nut and
withdraw problem related coil, replace it
with any other coil from the group. If the
problem remains it requires the
attention of a qualified service person.
15b. Disassembly of hydraulic valves
should be undertaken only by qualified
service personel or those knowledgable
with hydraulic compnents.
16a. Turn Feed Rate Knob counter
clockwise to open valve.
16b. Increase Feed Force Limit (to at
least 150 psi).
16c. Loosen pointer, turn knob
clockwise until it bottoms; tighten
pointer at "0".
17a. Readjust pointer. As in16c.