Electro Hydraulic and electromagnetic brake systems
Witton Kramer Brakes and Thrustors are manufactured by ATB Special Products at their site in Cradley Heath, near Birmingham in the UK, they supply large OEM's and distributors worldwide.
Prior to becoming part of Brook Crompton, Witton Kramer has a proud history which stretches back over 90 years.
In the 1980's and 90's, although the company offered a wide range of brakes and thrustors, growth was only slight compared to the that of the boom industries of the period, such as electronics and computers.
The GEC Small Machines company was sold to Hawker Siddeley in 1989, which in turn was bought by BTR in 1991, who merged with Seibe to form the Invensys Group. Witton Kramer is now part of Brook Crompton, a member of the ATB Group of Companies.
Spares & Accessories
A wide range of spares and accessories for brakes are available and standard spares are generally ex-stock.
Accessories include items for special requirements such as:
- Hand releases
- Proving indicator switches
- Lubricated pivot pins
- Self adjuster for wear on thrustor brakes
- Hydraulic over-ride with foot pedals for crane drives
- Drums, Drum couplings and Discs are also available
PM Brakes
Witton Kramer PM short-stroke magnetic brakes are suitable for operation on a.c. supplies from 110 to 575 volts and on all d.c. supplies up to 550 volts and comply with the relevant paragraphs of BS 466. The brakes are 8 hour rated in any period of 24 hours and the a.c. versions are fitted with internal silicon diode rectifiers. Series-wound d.c. brakes give full torque at the one hour rating, pulling in at 60% or 40% of the full-load current, The design incorporates a number of advanced features which reduce maintenance to an absolute minimum
Brake shoes can be removed and replaced quickly, without dismantling the brake. Also the pins securing the brake shoes are retained by large spring clips which are easily removed and replaced.
Torque can be adjusted by increasing the spring length if required/
PM Brakes
PMA Brakes
Perigrip Brakes
Perigrip Brakes
Thrustor Brakes
MEWK Drum Brakes
MTWK Drum Brakes
TDWK Disc Brakes
HD Thrustors
The HD Electro-hydraulic Thrustor has a compact single push rod design and can operate at any angle between horizontal and vertical.
The force is constant throughout the stroke and the push rod can be stopped at any point in its stroke without damage
The motor is Class F insulated as standard and the terminal box sides and cover are removable for ease of connection of cables.
All thrustors are available with alternative mountings for interchangeability with other types if required.
KT, KTF and KTX Thrustors
The KT Thrustor is a self-contained electro-hydraulic unit and is operated by a standard D63 or D71 cage induction motor fitted with a cast iron frame and steel terminal box.
A CSA approved version can be supplied in all frame sizes and also a modified version is available for DIP applications.
The TKF Flameproof Thrustor has an integral stator / rotor unit in a flameproof enclosure for use in hazardous areas, certified to BS229 for Group I & II gases (petroleum and accetone vapours).
The KT and TKF Thrustors are designed to meet all relevant British Standard requirements They are carefully inspected and tested to ensure that they comply with these requirements, and are safe in operation.
The KTX Thrustors are explosion proof thrustors certified to EEx de Zone 1 Group II gas groups A, B and C, with a temperature class T4 available in thrustor sizes 1503 and above these thrustors are slightly taller (50mm approx.) than our standard models.
Brake Control Gear
Brake control gear can be supplied for use with DC magnetic brakes with one or more of the following functions.
- Rectify the AC supply (1ph or 3ph) to provide dc for the brake coil.
- Reduce the brake operating time, eg to give a fast response on hoist brakes.
- Reduce the brake release time.
- Reduce the brake voltage after operation, to reduce brake coil heating, eg if duty cycle is arduous or ambient temperature is high.
Brake control gear comprises a combination of the following components depending on the application:
- Silicon or selenium rectifier
- AC or DC correction
- Surge suppression components
- Solid state or pneumatic timers
- Resistor
- Transformer
- Terminals and fuses
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