Twiflex MX Series Spring Applied Disc Brake Caliper

The Twiflex MX13, MX25, MX30 and MX40 series of disc brake calipers is suitable for use with discs of 12.7mm, 25.4mm, 30mm and 40mm thick respectively. The SMX caliper is only suitable for use with discs 12.7mm thick. Minimum disc diameter is 300mm.

The MX/SMX calipers may be used with any of the Twiflex series of thrusters and feature a patented link mechanism to ensure uniform pad wear.

Normally one or two calipers are used per disc, but the number may be increased depending on disc size. The brakes may be positioned at any angle around the periphery of the disc, but should ideally be mounted horizontally (i.e. at the 3 o’clock or 9 o’clock position). If the caliper mounting angle is greater than 10° from the horizontal, or on vertical shaft applications, it should be fitted with an inclined mounting kit or equalising link. A range of brake discs is available from Twiflex (see Disc and Hub Assemblies).

For pneumatic operation use dry, filtered and non-lubricated compressed air. Pneumatic brakes require a control valve, operated either manually or by pneumatic or electrical signal.

The ratings shown on the graphs are based on fully bedded in and conditioned brake pads with a nominal friction coefficient μ = 0.4. Twiflex disc brakes must be used with Twiflex asbestos free brake pads.

Effective disc radius = actual radius (m) – 0.033m.

MXEA Series

The EA actuator is a spring applied, electrically released unit designed for use with the Twiflex MX range of disc brake calipers. A 175W pancake motor drives a ball screw mechanism, retracting the brake.

A feature of the unit is a patented self-adjusting mechanism which maintains a constant air gap (and consequently braking force) between pad and disc as the pads wear.

The assembly is contained in a rugged, cast aluminium housing, designed for service in the harshest environments, which mounts directly to one arm of the MX caliper.

The MXEA is supplied complete with a solid state controller, suitable for all AC supply voltages, which converts the supply to the required DC output for the pancake motor. A 24VDC unit is also available. The brake is released when power to the controller is switched on, and applied when power is disconnected. Controlled application of the brake occurs, electrically damped by using the motor back E.M.F. and a damping resistor.

The controller is housed in a strong, steel, wall mounted enclosure (215mm x 215mm x 150mm deep), protected to IP44 as standard (higher rating on request).

Braking force adjustable to 50% of maximum.