Table 4-2. Unit Troubleshooting - Continued
TEST OR INSPECTION
AXLES - Continued
AXLE DOES NOT ENGAGE DIFFERENTIAL LOCK-UP
Step 1. Check for broken or pinched air line.
Check and replace air line (see para 4-9).
Step 2. Check if lock-up air chamber diaphragm is broken or chamber has internal damage.
Replace air chamber. Notify Direct Support.
Step 3. Air switch defective.
Replace switch. Notify Direct Support.
PUMP FAILS TO PRIME OR LOSES PRIME
Some pump operators mistakenly assume that the main pump is
fully primed when they see the first discharge of water and oil
come out of the priming pump discharge pipe, or when they see
a slight pressure on pressure gauge. Operate pump until it
emits a solid stream of water through its discharge pipe.
If desired, the pump may be running while priming. However,
priming may be more positive if the impellers are stationary.
At temperatures of 0 deg. F (-18'C) or below, use SAE 5W or
5W-20 engine oil in priming tank. Heavier oils are not suitable
at low temperatures.
Step 1. Battery has low state of charge.
Make sure battery is properly charged. If battery is in low state of charge, it may be difficult
to operate the priming pump at proper speed.