Operating Manual
Troubleshooting
2/12/04
29
the air valve fails to shift after its coil is activated. The most common causes of
reversing malfunction are as follows:
a) Something physically prevents the yoke from traveling its full stroke. Check
for any physical obstruction and remove it.
b) Air pressure set too low. Increase the air pressure.
c) Failure of the valve coils to energize and de-energize. This failure is readily
seen because the yoke will have physically switched the reversing switch, but
the pump direction will not have reversed. If this occurs, the problem is
either a malfunction in the reversing switch assembly, such as a faulty switch
or loose wire, or a mechanical or electrical problem within the control valve,
such as a faulty spool or valve coil.
5. OVER-PRESSURE PROTECTION- A 2800 psi pressure limit switch protects each
proportioning pump. Upon reaching this pressure, the switch automatically removes
power from both directional coils causing the pump to stall. When the power is
removed, both directional indicator lights will go off, which is the indication to the
operator of an over-pressure condition. As this is a non-lockout type of system, the
proportioning pumps will resume normal operation when the pressure bleeds off to
approximately 200 psi. However, the cause of the over-pressure condition should be
determined and corrected. The three most likely causes are:
a) A restriction in the gun on the high-pressure side.
b) Cavitation of the opposite pump.
c) Air pressure set too high.
6. CONTROL TRANSFORMER FUSE-
With the incoming electrical power
OFF and locked out at the source,
open the electric console and remove
the control transformer fuse. Check it
for continuity or simply replace it.
(See Figure 16.)
WARNING:
R
EPLACE THE FUSE WITH ONE
OF THE SAME RATING
. A
SUBSTITUTE MAY
DAMAGE THE EQUIPMENT AND CREATE A
POTENTIAL SOURCE OF INJURY TO THE
OPERATOR
. I
F THE FUSE FAILS A SECOND
TIME
,
FIND AND CORRECT THE CAUSE OF THE
FAILURE BEFORE CONTINUING
PROPORTIONING UNIT OPERATION
.
Figure 16. Transformer Fuse Location
7. PUMP YOKE ROLLER BEARINGS- Occasionally the roller bearings on which the
pump yoke travels will become clogged and seize up. Inspect and replace bearings
as required.
8. UPSTROKE OVER-PRESSURE- The proportioning pump pressure is higher during
the upstroke for both proportioning pumps due to the supply pump pressure. Adjust
the upstroke regulator so that the proportioning pump pressures are equal on both
strokes.
