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Yes, absolutely, only better.? In the X-ray world, we have a tube parameter called IHU or International Heat Units.? The units are BTU-seconds.? This is a measure of how much energy the anode (where the electrons strike to make X-rays) can receive and dissipate without damage.? The anode is tungsten embedded in a large copper bar.? The actual exposure, which lasts only a fraction of a seconds, imparts up to millions of BTU to the anode.? The copper absorbs the heat energy from the small tungsten button and, since the tube is under vacuum, radiates it away over time.? The higher the IHU rating, the longer an exposure can be, or more commonly in a busy medical setting, how often the tube can be energized.

The almost exact same thing applies to "overloaded" series motors, the only difference being that air surrounds the motor winding. The motor world simply lacks a catchy term like IHU.? The more massive the winding assembly is, the more heat it can store during extremely high loads, to be dissipated as the load decreases. That's why epoxy dipping and baking the pole windings does so much good.? Motor varnish is highly heat conductive so it draws heat off the windings and into the bulk of the assembly.

The epoxy used is 100% solids - no solvent, so there are no voids in the cured product.? Ideally the stator would be VPI (vacuum pressure impregnated) which is a process where the stator is placed in a pressure vessel.? A vacuum is drawn on it to remove all air from the space between the windings.? Then the epoxy is forced in under pressure.? This pressure causes it to penetrate all voids and compresses the tiny bit of air that remains until no bubbles exist.

Atmospheric dipping will work but ONLY if the technician leaves the stator in the epoxy for an extended period of time.? Our shop practice is 2 hours.

Under normal conditions, the motor amp profile is similar to an X-ray tube.? Very high current lasts only a few seconds while accelerating up to speed.? Then it drops to whatever is required to overcome drag and rolling resistance.

Climbing hills, which is a special condition, is a whole different situation. There, there is a high amperage load for an extended period of time.? I never engaged my controller bypass on steep hills.? I just creeped up at the controller current limit of 450 amps.

I also had a very good temperature indicator.? Don't rely on the cheap chicom indicators which rely on thermistors.? Instead, use a bare tipped thermocouple, covered with heat-shrink and wiggled deep in the field winding before the stator is dipped.? Spend the money on a good industrial temperature indicator.? I bought one from Omega Engineering for about $75.? It ran on from 5 to 45 volts.? It drew such a tiny amount of power that I simply tapped my pack at the 45 volt point.? It can handle any type of thermocouple and displays the temperature to one decimal point.? I have a thermocouple calibrator on which I maintain an INIST-traceable calibration.? My indicator was always spot-on right down to the decimal degree every time I tested it.

The class H epoxy is rated to 140 deg c.? I set my limit to 100 deg C.? for testing I mounted a small camera and a process control infrared temperature pyrometer to look at a brush and holder assembly.? I was looking at temperature and for the trailing arc length.? The brushes got considerably hotter than the field which is why I limited the field winding to 100 deg C.

The arcing phenomena can be controlled by advancing the brush assembly about 5 deg.? That requires a bit of machining but it can be done with a die grinder and a steady hand.? Interpoles, also called commutation poles that fit between the main poles, completely solve the arcing problem but I could not find a pole piece in the catalog small enough to fit the Terrel axle motor's main field windings.? machining poles was out of the question before on-line CAD-CAM services.

All the above applies to the stock motors.? The D&D motor is vastly more rugged.? Someone correct me if my memory is faulty but I think it contains interpoles which enables it to withstand heavy overloads.? I installed one on a customer's 72 volt car.? I ordered a 45 volt motor.? I'm not recommending this unless you have the proper test equipment to evaluate the situation.? This worked out great.? I equipped the motor with a thermocouple temperature indicator and never saw more than 80 deg C, even after a long hill climb.

As always, one must consider the load on the axle.? Either my mods or the D&D motor applies much more torque than the axle was designed for.? A guaranteed gear breaker is wheel hop during hard acceleration.? This can partially be addressed with better shocks.? A good friend owns the local NAPA dealership.? He received a lot of technical info from the major manufacturers that the typical NAPA store makes available to the customer.? We picked out a shock with more upward damping and less rebound damping. This limited how high off the road the rear axle can rise off the road and allows the springs to force the wheel back down faster. this limits how much the motor can increase speed while the tires are off the ground, thus limiting the inertial load on the gears when the wheel(s) touch back down.? The result is a harsher ride but gears that live.

I just can't recall the shock we selected.? Yellow and blue come to mind so probably Monroe.? Now that everything is online, shock selection will be much easier.

with either motor, fitting a high pressure blower to the motor tremendously increases the overload capability.? You must buy a high pressure blower and not an ordinary squirrel-caged blower. There are high pressure squirrel-cage blowers but they must be selected by catalog spec.

All high pressure blowers are noisy.? very noisy.? So you'll probably want to fit a Klixon thermal switch to the motor field. I selected one that turned on at 40 deg C and turned off at 35.? I think Digikey has them.? Granger certainly does.? The type I'm talking about looks like a slightly squared cylinder about an inch long.? It can be high temperature RTV'd to the field winding.

The blower inlet must be flex-hosed into the passenger compartment to prevent the intake of rain and road debris and in colder climates, to keep out ice and snow.? It is loud.? I fabricated a muffler out of fiberglass and polyester resin that knocked the noise down to a low roar.

out of advice for now,
John