Nippon Pulse linear shaft motors are available from Micromech in the UK.

The underlying motor technology is a shaft of rare earth-iron-boron magnets inside a stainless steel tube, and a 'forcer' of cylindrically wound coils which can be supplied with optional Hall effect devices.

There is no iron in the forcer or shaft thus giving zero cogging, and there is no contact between the shaft and forcer between which a non-critical 0.5 to 5mm air gap.

"There is no variation in force as the gap varies over the stroke of the device," said Micromech.

The most recent motor is the L427 series, with a 5mm air gap for applications where there is the potential for matter to stick to and build up on the shaft where it will prevent the motor from jamming and will increase the time between cleanings.

Usable stroke length is 100mm to 4.6m.

The motor’s peak force is 450N, while its force constant is 31(Kf)N/Amp.

Other features include a 42.7mm shaft diameter, 3.6A continuous current, a 14A peak current, a 10V/m/s back EMF, and a 3kg forcer weight.

For more information, see http://www.micromech.co.uk