The market for battery driven wheel drives is vast, but hitherto the
technology has been bulky, inefficient and expensive, and the take-up has
consequently been slow. Now, Kollmorgen hopes to change all that with a
development that is already being put to good use in China
There are many potential applications for battery driven wheel drives out
there, but available technology - usually involving a standard dc motor
and worm gearbox combination - is inefficient and draining on battery
reserves, as well as being bulky, heavy and expensive. Now there's a
cheaper, more elegant alternative, derived from the 'pancake' servomotor
format, which is now being incorporated into bicycles by a manufacturer
in China.
Kollmorgen's Powertrac hub motor, which is available in the UK from
Heason Technologies, features an ironless flat armature configuration
with integral helical gearbox, all sealed to IP55. The stamped armature
has a low inertia and inductance, allowing rapid acceleration with almost
instantaneous torque available from very low speeds. In the bicycle
application, Powertrac units are designed to be spoked directly to the
rear wheel or even moulded into a urethane tyre.
The bicycle will manage speeds up to 15mph and cover a distance of 20
miles between charges. For extended travel between charging, it can be
pedalled in the normal way. it is a clean, efficient and environmentally
friendly form of transport that requires no special license, insurance or
road tax.