Clutch Disengaging Too Early During Startup

Dear members,

We have frame 6B GT. Recently, the jaw clutch is getting disengaged even before reaching crank speed, and subsequently the machine trips on STARTING DEVICE TRIP.

There are no changes in the Diesel Engine and torque converter. Diesel Engine attains the speed of 2000 rpm. Turbine breaks away successfully, but between 500-600 rpm the jaw clutch gets disengaged. We found all parameters are to be normal, but could not find out the reason for this and then solution.

pls help with your suggestions..


If the torque converter has a solenoid for spoiling have you checked that it's working correctly?

What turbine control system does the unit have? Can you collect data or trends with the control system?

What kind of controls does the diesel have? If it's electronic, it might be a problem with the module. If the diesel uses solenoids to increase the fuel/speed/torque then one or more of the solenoids may not be functioning correctly

Has someone monitored the fuel rack position during acceleration to see if it's working correctly?

The design of the jaw clutch teeth (and they should NOT be excessively rounded off!) Is that the torque from the starting means will keep the clutch halves engaged until the speed of the unit over-runs the speed of the starting means causing the teeth to disengage, at which point the springs of the jaw clutch will open the clutch. The limit switch will tell the diesel to slow down. Have you checked the adjustment and operation of the limit switch? Also if the teeth of the jaw clutch are excessively rounded they not keep the clutch halves engaged during the entire acceleration.

That's about it. It's fairly simple and reliable. If there is any interruption in the torque being transmitted the jaw clutch teeth will disengage prematurely. Especially if the teeth are excessively rounded. And mamy people never think to check the condition of the teeth. Many problems have been caused by the jaw clutch limit switch getting disturbed or the mounting bolts coming loose--including the screws holding the switch inside the enclosure (if it's a typical mechanical switch and not a proximity switch).

Also, be sure all the electrical connections and terminations for the various components are tight.

Please write back to let us know how you are fare in resolving the problem and what you find.