Altec DRM 12, Manual

Page: 60 / 143

Section 7 — Maintenance • 55
Symptom
Unit will not
feed.
Test Procedure/Corrective Action
When tripped, the panic bar will mechanically deflect a cam attached to the first spool of the
main control valve. This will in turn shift the valve to dump oil directly to tank. Reset panic bar
by returning the red valve handle to the neutral state.
Disconnect the harness from the controller. Using a test light, or multimeter, probe pin 13 (module
ground) and pin 14 (module power) to ensure that power is delivered to the module. If no power
is detected, confirm that the connection is adequate, and the harness is not damaged.
The controller receives a drum speed signal from a magnetic speed sensor. If the controller
does not receive the signal, or the signal (rpm) read is too low (below 2,000 rpm), it will not allow
forward/reverse motor functions.
Engine throttle is not in the high position. The engine throttle needs to be in the high position
running at about 2,600 rpm at Idle for the feed system to activate.
Engine not increasing in speed when shifted from the low to high position. For proper throttle
adjustment, refer to the engine manual.
The drum may be jammed preventing it from rotating. Check the drum shaft for rotation. If no
movement is visually detected, refer to the section labeled Clearing Feed System and Discharge
Chute in the manual.
Controller is not receiving a signal from the magnetic pickup. If the controller is not receiving a
signal from the magnetic pickup or the signal is too low, the system will not allow the forward/
reverse function of the feed wheel.
Check the magnetic pickup output at full rpm for correct signal. At full drum rpm, the magnetic
pickup should read 2.5 VAC. Refer to Figure 7.8 for the correct frequency to rpm conversion.
This can be measured by disconnecting the magnetic pickup from the harness and measuring
frequency (Hz) across the connector terminals.
Verify all the wires intact and the connectors between the magnetic pickup and controller connected.
Proper adjustment of magnetic pickup end should be approximately 0.030” to 0.050” from rpm
sprocket on drum shaft. Refer to Figure 7.9 for clarity.
The valve is activated by a signal delivered from the controller. It shifts when the controller
energizes one of two solenoids. The VF solenoid delivers flow in normal operation. The VR
solenoid reverses flow during normal operation, and more specifically during the activation of
the EFC function.
When the control bar is in the forward feed position (pulled towards the rear of the unit), it shifts a
spool on the main control valve through a series of linkages. The spool directs flow to the motor
allowing it to feed forward or in reverse (depending on the control bar position).
Disconnect the connector labeled VF/VR. Using a test light, or multimeter, probe the pins to en -
sure that power is delivered to the solenoid. You can also check the voltage from pin 1 to ground.
It should be 12 V. If no voltage is read, check to make sure that the harness is not damaged.
For the feed roller to operate, the system has to produce both pressure and flow. If no material
is in the infeed chute, the rollers will only require about 150 to 200 psi (10.3 to 13.8 bar) to turn.
When feeding brush and logs, the system normally requires 1,000 to 1,500 psi (68.9 to 103.4
bar). The system relief is set to 2,500 psi (172.4 bar).
If the feed roller does not move when the feed control bar is in the forward feed position, and
all the previous checks show that the system is functioning properly, install a pressure gauge
in the system. The main control valve has a quick connect port located by the panic bar spool
which will allow for connection to a pressure gauge. If the feed wheel is in a bind, the pressure
should read 2,500 psi (172.4 bar). Another option to confirm hydraulic flow to the feed wheel is to
install a pressure gauge in the hose going to the P (or A) port of the EFC valve. With the control
bar and valve in the forward feed position, this should read approximately 2,500 psi (172.4 bar).
Possible Cause
Panic bar tripped.
Controller not
receiving power.
Drum speed too
low.
EFC valve
directing oil to
the feed roller
motor.
Oil pressure is
too low.
Figure 7.7 — FeedSense
®
Controller Troubleshooting