914G WHEEL LOADER HYDRAULIC QUICK COUPLER ATTACHMENT THIS MODULE INCLUDES Testing And Adjusting Caterpillar

Troubleshooting

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Electrical shock or death may result. Remove all rings, watches, etc. prior to doing any electrical work.

Low Voltage

Operating direct current (D.C.) power units efficiently requires proper voltage. Any attempt to operate below the minimum required voltage could cause system failure.

Signals which point to low voltage are:

1. Motor running at reduced speed.

2. Solenoid valves not shifting.

Minimum voltage readings are as follows:

1. The minimum voltage between the motor stud and ground is 9.0 volts at maximum load conditions.

2. The minimum voltage between the valve solenoid power wire ("hot lead") and ground is 9.5 volts at maximum load conditions.

Causes for low voltage are:

1. Battery capacity too small.

2. Cable ends not electrically secure to battery cable. (solder if necessary).

3. Battery cable size too small for load and length of run. Copper #1 automotive battery cable is the recommended minimum size. Larger copper battery cable, #0 or #00, may be required for cable lengths over 16 feet to keep performance from deteriorating.

4. Ground cable size not equivalent or larger than battery cable.

5. Bad joints where cable ends are bolted to battery, motor solenoid, starter switch, ground and etc.

6. Burnt contacts on motor solenoid or start switch.

Check for low voltage as follows: (a volt meter will be required)

1. On vehicles equipped with an alternator, the voltage should be approximately 13.5 volts with no electrical accessories operating and the engine running.

2. Operate pump unit under maximum conditions; this would be either under full load or when pump is running over relief (cylinder dead headed). Use the volt meter to probe each connection, cable end, and cable from the battery all the way back to the motor stud and note the voltage loss. Make the necessary repairs to increase the voltage above the minimum required.

D.C. Motors

Motors should be serviced periodically to insure good performance.

Service as follows:

1. Remove head assembly from motor.

2. Check sleeve bearing in head assembly for wear.

3. Place a few drops of oil on felt liner in head assembly.

4. Check brush set for wear and replace if necessary.

5. Blow dirt and dust out of motor housing and check for shorts, burnt wires, or open circuits in the field coil assembly.

6. Check armature and commutator for shorts or open circuits.

7. Check ball bearing on motor shaft, a growling motor can be caused by bad bearings.

8. Check for excessive "end play" of armature and add thrust washers as required.

9. If there is an excessive amount of water, condensation, or rust in the motor, a small drain hole may be drilled in the motor case on the low side of the motor depending on the mounting.

10. The Monarch® D.C. motor turns counterclockwise when viewed from the drive end. Check when replacing motor with new one.

11. If motor fails to turn the pump, check the pump by turning drive shaft by hand. It may be locked up.

Electrical Switches

Push button, toggle, rocker and manual motorstart switches.

Defective switches are a common cause of electrical malfunctions. What seems to be a serious defect can often be caused simply by a faulty switch.

Troubleshooting can be done by any one of three methods:

1. Use a "continuity light" to test switch.

2. Use a circuit "test light" to test switch.

3. Remove the wires from the switch and "touch" them together in the proper order to operate the system.

Motor start solenoid switches.

NOTE: When testing for a faulty solenoid switch use an Ohm meter, continuity light, or test light; and check all functions as described above.

3-Post solenoid Switch with case ground.

3-Post Solenoid Switch with case ground.
(1) '+' terminal. (2) Control circuit terminal. (3) Power cable terminal to D.C. motor.

The three-post solenoid switch with case ground is wired and constructed as follows:

* The large post (1) marked "Bat" must be attached to the cable leading from the battery.

* The small post (2) connects to the control circuit. (Push button, rocker switch, or toggle, etc.).

* The shared "Hot" lead from the control circuit must also be attached to the large post marked "Bat".

* The remaining large post (3) attaches to the cable leading to the D.C. motor.

Shorts, Grounding Faults, And Open Circuits

In control wiring, shorts can only occur when "hot" lines (lines connected directly to the battery) come in contact with ground. A short will either cause a fuse to blow, if there is one, or burn the wire off at its weakness point. Likely spots for shorts are switches, electrical strain reliefs, electrical junction boxes, or a control cord that has been pinched or cut.

Grounding faults are much like shorts except they occur on the opposite side of the electrical component. (Valve solenoid or motor solenoid start switch). A "ground fault" will cause the coil in the motor solenoid or valve to remain energized. This type of failure can happen because switching is done in the ground wire due to construction of the motor solenoid switch. (See electrical switch section). Likely sports for "ground faults" are the same as shorts.

An "open" circuit is simply a break which prohibits current flow. Likely spots for "open" circuits are the same as shorts.

Solenoid Coils

Coils are used in solenoid operated valves and solenoid start switches. Failures can be caused by vibration, water, improper voltage, or corrosion. The best way to test a coil is with an ohm meter. The meter should read some value of Ohms. An infinite reading means that the coil has an open circuit. The reading between any lead on the coil and the "housing" should be infinite unless there is only one lead wire and the coil is grounded to the housing.

Electrical Polarity

The motor and valve supplied by Monarch® can be used on either positive or negative ground systems. In these units there is a capacitor connected on the switch which must be "polarized". They are normally sent out for negative ground systems and if used on a positive ground system, the capacitor must be turned end for end as the (+) sign must face the most positive side of the circuit. Failure to align properly will cause the lead wire to "blow" off the capacitor, which in turn could make a "ground fault" and cause the motor to run with no control.

Seal Failure

A cut or damaged lip on the seal, a bad fit on the outside diameter, or a seal that is "blown" partially out of the seal cavity will allow air to be drawn into the pump and will be evidenced by foaming oil and a pump that will not reach high pressures. Repair as needed.

Reservoir Problems

1. Clear oil flowing out of the fill hole usually points to one of the following:

A. Cylinders were not fully extended when the reservoir was filled.

B. Reservoir is too small for cylinders total stroke.

2. Foamy oil flowing out of the fill hole points to the following:

A. Air is present in the system cylinders and fluid lines. The response usually is "spongy" and the cylinder moves with "jerking" motion.

B. There is no drop tube or "down spout" on the return line so that the oil is not returning to the bottom of the reservoir.

C. The return oil velocity is excessive; to correct, add a flow control valve to slow velocity, increase size of "down spout", add a diffuser, or use a larger reservoir to increase depth of oil above the end of the return tube.

D. The reservoir is too small to supply the volume of oil required by the cylinders and the pump picks up air when the oil level drops below the suction pick up tube.

E. Damage to pump seal.

3. Water in the oil.

Water can enter the reservoir through the fill hole if the unit is left outdoors or washed with a high pressure washer. Protect the unit, whenever possible, and change oil regularly to minimize problems. In cold weather the water will freeze and the pump will not work until the ice melts.

Relief Valve Pressure

Relief valve pressure too high.

Symptoms:

1. Amp draw and battery drain excessive when system is "dead headed".

2. Motor RPM is slow in comparison to full load system operation.

Repair procedure:

1. Turn relief valve adjusting screw counterclockwise. Use a gauge attached to the high pressure line to record the proper pressure setting, 10335 kPa (1500 psi).

Relief valve pressure too low.

Symptoms:

1. Motor RPM is "faster" than normal.

2. Cylinder will not extend.

3. Excessive turbulence in the reservoir.