GE MS5001M Torque Converter Dropping Out Prematurely


Thread Starter


MS5001M, Speedtronic Mark I, Cummins V8 Diesel and Twin Disc Torque Converter

One of our units is not accelerating passed 870RPM and we think it has something to do with our starting means. We having a Cummins V8 diesel and twin disc torque converter.

Upon each start the jaw engages and allows the turbine generator to accelerate to light off but at 870RPM the jaw disengages and the diesel goes into cool down. The turbine then doesn't accelerate. We also tried forcing the clutch closed during startup and still had the clutch disengage.

The diesel was first suspect but when we put a tachometer on it, the diesel supplied a constant 2500RPM to the torque converter which eliminates the possibility of a diesel problem. We then thought the torque converter may be sucking air or not supplying enough oil so we checked the foot valve and oil pressure from the charge pump (both found to be acceptable). We also changed out the charge pump and we had the same results.

We finally bit the bullet and removed the torque converter and sent it out for repair. The rep did not find anything mechanically wrong with the unit and replaced the seals and one worn bearing for the charge pump shaft. I am installing the refurbished torque converter today and will go for another test run but I am anticipating running into the same problem.

As a note I test ran the unit successfully to full speed no load and base load (4) times before the thanksgiving holiday. When the unit started up the following Monday we rain into this.

Anyone have similar issues?
Do you have a diesel engine Lube Oil Pressure switch something like 63QD? this can be faulty and will cause the diesel to drop to cooldown. Have you checked the clutch limit switch, although you say you forced the clutch, it's just a second thought.

If the diesel decelerates and goes into cooldown, then it wouldn't seem to be the diesel L.O. pressure switch.

But, if the jaw clutch closes and then during acceleration something causes the jaw clutch limit switch (33CS-1) to change state that would tell the diesel to decelerate and go into cooldown, opening the jaw clutch and causing the unit to trip (most likely on some kind of bog down (failure to accelerate and/or actually decelerate).

Jaw clutch limit switches can be somewhat difficult to adjust properly, and if there was a loose wire or a bad contact or a bad switch, or if the switch was just mechanically loose and subject to vibration, that could cause problems.

I'm not personally familiar with Mark I control systems, but I would imagine the jaw clutch does have a limit switch--to tell the starting means when to shut down/go into cooldown during starting when the turbine speed over-runs the jaw clutch speed.

If there's no jaw clutch limit switch, then there would have to be either some kind of timer or speed level detector to shut down the starting means, and either of those elements (in an analog control system) could be failing intermittently or need adjustment.

Please write back to let us know how you fare!

Mark I controls did use the 33CS-1 limit switch on the jaw clutch.

The main differences between Mark I controls and Mark II controls:

1. Back plane power supplies were lower voltages - Mark I had Plus 50 vdc and Minus 50 vdc power supplies and Plus 28 vdc; Mark II had Plus 12 vdc and Minus 12 vdc and Plus 5 vdc and Plus 28 vdc power supplies.

2. The analog controls made use of operational amplifier integrated circuits (709, 749 & LM 301), replacing discreet transistors.

3. Much of the sequencing was done with 7400 series integrated circuit AND, OR, NAND type gates replacing electromechanical relays. Relays were still used to drive outputs (no solid state relays).
Most of the contact input field devices were the same on both controls. The servos were different due to the lower voltages.

The later Mark II panels also replaced the exhaust temperature control with the Integrated Temperature System (ITS) microprocessor based control which also included the combustion monitor. This was never used on Mark I, to my knowledge.

Thanks very much for the information. I've worked on a couple of Mark II-equipped units, replaced many with Mark V, Mark VI and Mark VIe. But, I've never worked on a Mark I unit, though I have reviewed some old Mark I elementaries.

One of the things that's so good about GE-heavy duty gas turbine control philosophy is that when it came to field devices and instruments and systems they didn't try to re-invent the wheel every time they introduced a new control system. In fact, because the control systems were designed by a different division of GE (not the turbine products division(s)) they were usually designed with existing I/O and systems in mind for a "seamless" replacement.

In my time beginning with early Mark IV control systems this is what I've experienced, anyway--the field devices and instruments and systems don't change very much, and when they do it's not a complete change of nearly everything, it's just kind of gradual.

Again, thanks--and Happy Holidays to you, otised, and to everyone at and following these threads! And, most of all, best wishes for a peaceful, healthy and prosperous New Year!