DIFFERENTIAL LOCK, 7U1818 - Caterpillar

Keep engine speed low until the engine oil pressure indicator light goes out. If it does not go out within 10 seconds, stop the engine and investigate the cause before starting again. Failure to do so, can cause engine damage.
The hydraulic activation control lever must be in the UNLOCKED position, before the hydraulic controls will function. 1. Allow the engine to warm up at LOW IDLE for at least five minutes. Engage and disengage the equipment controls to help speed warm up of hydraulic components.When idling the engine for warm-up, observe the following recommendations:* In temperature above 0°C (32°F), warm-up requires approximately 15 minutes.* In temperatures below 0°C (32°F), warm-up requires approximately 30 minutes.* In temperatures below -18°C (0°F) or if hydraulic functions are sluggish, more time may be required.2. To warm up the hydraulic oil, turn the engine speed dial to medium engine speed. Run the engine for about five minutes while intermittently holding the bucket control lever in the bucket dump position.3. Turn the engine speed dial to the maximum engine speed. Run the engine for an additional five minutes while intermittently holding the bucket control lever in the bucket dump position.This will allow the oil to reach relief pressure, which causes it to warm more rapidly.Cycle all controls to allow warm oil to circulate through all cylinders and lines. 4. Observe the gauges and indicators frequently during the operation.