Posted: Mon Aug 18, 2008 3:51 pm
I've seen more than one Series motor blown up due to popping out of gear, which is more likely when changing gear without a clutch. The added roatational inertia of a flywheel/clutch helps if this happens giving you just enough time to get off the throttle. A rev limiter would help protect the motor in these circumstances. It would also help with higher voltage vehicle where it is possible to over-rev in gear.
I had a stuck throttle on the Scirocco because of a damaged liner in the original cable. There was no way the brakes would hold the motor back and my normal instinct was to clutch out. This stopped the vehicle accelerating, but now the motor (the commutator at least) was in danger of bursting. The inertia of the clutch and flywheel gave me enough time to feather the clutch to control the motor speed whilst still being able to hold the car on the brakes. I was then able to go for the ignition switch.
A clutch also made control at low speeds much easier. It's difficult to get really fine control on a high voltage system an I would use a little slip when parking.
The aditional weight was fairly small compared to the weight of a series motor, but the standard clutch did struggle at times. I could get the clutch to slip accelerating hard in third gear.
As for loads on the bearing, a typical motor output bearing would be something like a 6006 deep grove ball race; 30mm I/D, 55mm O/D and 13mm wide. It's rated for a dynamic radial load of 11,900 Newtons @ 100,000 hour life expectancy. The axial rating would be about 25% of that.
I had a stuck throttle on the Scirocco because of a damaged liner in the original cable. There was no way the brakes would hold the motor back and my normal instinct was to clutch out. This stopped the vehicle accelerating, but now the motor (the commutator at least) was in danger of bursting. The inertia of the clutch and flywheel gave me enough time to feather the clutch to control the motor speed whilst still being able to hold the car on the brakes. I was then able to go for the ignition switch.
A clutch also made control at low speeds much easier. It's difficult to get really fine control on a high voltage system an I would use a little slip when parking.
The aditional weight was fairly small compared to the weight of a series motor, but the standard clutch did struggle at times. I could get the clutch to slip accelerating hard in third gear.
As for loads on the bearing, a typical motor output bearing would be something like a 6006 deep grove ball race; 30mm I/D, 55mm O/D and 13mm wide. It's rated for a dynamic radial load of 11,900 Newtons @ 100,000 hour life expectancy. The axial rating would be about 25% of that.