 TL SERIES TOGGLE LEVER CALIPER BRAKES TL SERIES TOGGLE LEVER CALIPER BRAKES are the largest known spring applied, hydraulic released caliper brakes in the world. Features include a stackable design allowing 1 to 4 calipers to be mounted in a common frame and spring force compensation by toggle mechanism resulting in constant braking torque. The TL series brake is particularly well-suited to accommodate very high braking torque requirements in the harshest environments. |
TL series brakes are ideally suited for use with equipment such as SAG mills and rock crushers.
These images show a 36 ft (11 m) by 17 ft (5m) 16000 horsepower gearless SAG mill with a 470" (1194cm)
diameter by 5" (12cm) thick flange-mounted disc. This mill is fitted with two TL250 series caliper assemblies housing three calipers each. The brakes are powered and controlled by a Johnson three mode
hydraulic power unit with set, creeping and inching capabilities,
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Design Features 
Caliper shoes are attached with stainless steel shoe pins. These pins Incorporate countersunk lubricating holes, tapped pin-pulling holes, and a pin retention groove.  Caliper levers incorporate a unique toggle mechanism to compensate for spring force. This ensures constant braking torque.  The system is powered by a hydraulic power unit incorporating a manifold fitted with two 010 valves (shown in blue) to accommodate brake set, creeping and inching modes. |
*Shown here three high model 
TL series brakes are well suited for use with conveyors requiring high torque braking.
Shown here is an 8000 ton per hour regenerative conveyor. This conveyor is 4600 feet
(1402m) in length and has drop of over 850 feet (259m). The system is fitted with eight
TL075 brake calipers and is controlled by two Johnson HU058CPD hydraulic units.
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| Note: All of the above TL brake calipers can be made in stacks of up to four individual brake units. Depending on the stackup the TL brake calipers can provide a torque of up to four times what is shown in this table. | ||||||||||||||||
The brake size must be chosen to give required braking torque and to dissipate the energy during stopping without over heating the disc. Brake torque is often related to drive motor torque by an arbitrary service factor typically 75% -100% full load torque for crane travel and similar inertial loads which tend to be self stopping or 150% -200% for crane hoists and other overhauling loads. If a precise stop time or distance is specified, then the brake torque must be calculated. Motor FL torque is given by: MT = [(kW x 9550) / rpm]Nm or [(HP x 5250) / rpm]Lbft Dynamic Imperial Brake Torque is given by the equation: DT= (Af X 0.50 X (D-f)) / 24 Static Brake Torque is given by the equation: ST= (Af X 0.40 X (D-f)) / 24 DT = Dynamic Brake Torque ST = Static Brake Torque Af = Applied Force D = Brake Disc Diameter f = swept face |
