With its demand for equipment with extreme reliability and ruggedness often for operation in confined spaces, the defence sector is a prime market for PMW’s compact motors.
The company’s brushed printed armature DC motors are powering applications in military installations and vehicles and are ideally suited for applications calling for low profile motors in environments where they may have to remain operational in temperatures of up to 150°C (302°F). These include motors for cooling fans, air movement fans, turret turning motors and positioning systems.
Brushless motors from PMW have been manufactured for wheels and winches for bomb disposal robots, and for propulsion units for underwater use.
Application: a slim fan for the Challenger 2 tank
Asked to manufacture a motor to drive the cooling fan for the auxiliary power unit (APU) of the Challenger 2 tank, PMW created a new design of its flat profile brushed DC motor to accommodate twin armatures. This effectively doubled the power output of the unit with only a minimal increase in its axial length.
During the development PMW carried out extensive tests to ensure that all internal components were optimised for the specified conditions. The tests resulted in modifications to the bearing grease, brush materials and armature in order to withstand the temperature regime, plus additional RFI suppressing components to meet the rigorous electromagnetic compatibility (EMC) requirements.
The motor achieved compliance with exacting military standards, with the DEFSTAN 00-35 British Ministry of Defence test regime requiring motors to be subjected to -20°C (-4°F) and +150°C (302°F) for two hours each. The motors then faced endurance tests of 750 hours of operation at 65°C (149°F) followed by 85°C (185°F), then by simulations of dust, sand and driving rain.
With its twin shaft seals, the printed armature motor also achieved an environmental IP55 rating.
Application: mission critical air movement
Brushed printed armature DC motors from PMW are powering cooling and filtration fans in chemical, biological, radiological and nuclear (CBRN) air filtration systems in military vehicles and installations. Powerful impellors draw air through particle pre-filters and gas filters to deliver clean, safe air to personnel and electronics systems.
PMW’s printed armature motors are ideally suited for this duty. Their use of axial air gap motor technology offers instantaneous, inertia-free torque to ensure the fan blades accelerate to running speed in the minimum time.
Minimising the size and weight of the units is frequently essential in military applications, and the very low profile of this type of pancake motor makes it ideal for attaching directly to the impellor for use in spaces where a traditional can-shaped motor would be too bulky.