Conveyor belt Drive transmission


Thread Starter

Charlie Griswold

I have two motors running independently, powering their own automation operations. It is my hope to disengage each motor from their drive systems
and have them both engage into a third system. The disengagement and engagement I plan to accomplish with (4) four solenoid actuated, axially mounted clutches.

I believe a differential gear box is necessary to combine the two inputs into one and account for different drive characteristics in the two motors.
Do you guys agree this can be done? What type of differential box would I be looking for? Are there specialty clutches, or transmissions, built for this kind of operation?

I plan to stop each motor before engaging and disengaging the clutches. If I was running at 3000 rpm, 400 with each motor, do you think I could get away with engaging/disengaging on the run?

Charlie Griswold
Automation Engineer
ph: (858) 202-9099
fax: (858) 202-9001
3595 John Hopkins Ct.
San Diego, Ca. 92121
[email protected]
It may be difficult for anyone to answer without more detail. It could be worth looking at torque converters if you want to do it on the run. Is it going to be more cost effective than having the extra motor?

Vince Dooley
Responding to Charlie Griswold's query dated Wed, Aug 29, 2001, 2:06 pm:

I would not recommend the two motor configuration that you proposed, i.e., physical coupling to one load (ca 19 Hp). This position is based on the presumption that you are talking about AC induction (asynchronous) motors.

Search the List Archives for technical discussion. Both theory and case histories showed why the practice of physically coupling two (or more) motors should be avoided... unless you are extraordinarily lucky. The subject titles were:

"Motors in Tandem" or "Motors Assisting Each Other."

Phil Corso, PE
(Boca Raton, FL)

Donald Pittendrigh

Hi All

I missed the original posting but the conventional
setup for motors in tandem on a conveyor is
each motor is coupled via some form of fluid
coupling to a gearbox, and the gearbox outputs
are on a common shaft. Load balancing is acheived
by regulating the volume of oil in each coupling.

I would certainly try to avoid direct coupling the
2 motors as there is no simple way to balance
the load unless the motors are driven by VSD's

Donald Pittendrigh

Charlie Griswold

Everyone has been helpful to a large degree. I think the problem is that the majority of Engineers on the List have an Electrical backround. Advising me that two motors will have different speeds, and would undoubtably carry
different loads running in tandum is understood. This can be assumed practicallly unavoidable from the electrical/control side.

I was asking if a differential gearbox would be a way to go as a mechanical solution to account for this effect?

Slip clutches? I was looking to use friction, multi-plate, Double-cluthes from Orttech. They can slip, but not continuously, and only when the
maximum load is exceeded. To have the clutches sliping continuously to accommidate minor load discreptances would minimize my drive torque, would it not?

Fluid couplers? I had not heard of these as a technique, or product, before and will look into them. They sound like they may be the best solution.


Charlie Griswold
Automation Engineer
[email protected]

Responding to Charlie Griswold's Sep 6, 9:40 am, reply:

I apologize for misunderstanding your query. The use of a differential-gear won't solve the basic problem which is related to the torque-angle of one motor with respect to the other. Although the gear box solution compensates for different speeds, sooner or later it will "lockup" and then it can not compensate for the torque-angle separation of both mtors.

Some sort of slippage is required. Donald Pittendrigh's recommendations for a fluid coupling, a VFD, and even a friction clutch, is correct. Although the mathematics prove it (see aforementioned archive on subject) there are still some skeptics.

One last comment. The "luck" I alluded to in my earlier response was related to the difference between the torque-angles of both motors, For
success the difference between them had to be minimal. While theoretical, such constraint is improbable.

Phil Corso, PE
(Boca Raton, FL)