7032 SOUTH 196th - KENT, WA 98032 - (253) 872-0141 / FAX (253) 872-8710
OPERATION / MAINTENANCE MANUAL
MODEL 50 VIBRATORY HAMMER WITH MODEL 260 POWER UNIT
VII-4. Troubleshooting: Power Unit Electrical (Continued...)
VII-4D. Troubleshooting: Oil Pressure Sending Unit (CAT Engines Only)
An electric "OIL PRESSURE GAUGE" is provided to monitor engine oil pressure. The CAT
oil pressure gauge is wired to an oil pressure sender that forces the gauge to read zero
pressure when the power is turned on. The CAT sender is a variable resistor that is normally
grounded and slowly decreases grounded voltage as pressure is delivered to it. As the
voltage decreases, the pressure gauge reading increases. To test the sender, disconnect the
wire leading to it and place one OHM meter lead on the sender terminal and the other lead
on the engine. It should show maximum resistance. If not, replace it. CAT ONLY.
VII-4E. Troubleshooting: Oil Pressure Sending Unit (CUMMINS Engines)
The engine oil pressure gauge on the Cummins engine is wired to a variable resistor that
goes from zero resistance when not pressurized to full resistance when at maximum
pressure. When the power switch is turned on the gauge reads zero. When the engine is
started the engine oil pressure increases and the variable resistor begins to ground out as
engine oil pressure pushes on it. If the gauge continues to read zero, the sender may be faulty.
To test the sender, disconnect the wire from the pressure gauge and place one lead of the
OHM meter on the sender terminal and the other lead on the engine. OHM meter should
read zero resistance. If OHM meter shows resistance then replace it.
VII. MODEL 260 POWER UNIT (Continued...)
Page 7-12
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