Overload Protection Unit

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Overload Protection Unit

Conpura’s overload protection unit is intended for application on gear motors. It protects the machinery from failures. The overload protection is particularly well suited at high security operations at slow speed operations – we have experience of thousands of this kind. The switching accuracy is very stable.

Product Description


overlast02The overload protection unit is designed as a tension bar with a limit switch. It is mounted between the gear housing and a lug on the machine.

Value of breaking force = Max allowed torque  = (kpm)
R                     (m)


The tension bar concists of a cylindrical housing with an adjustable cover. A piston with pistonrod is located in the housing. Between the piston and the adjustable cover is a spring washer assembly, which is compressed by the tension bar under overload condition. The setting of the cover regulates the brake force. The piston is fitted with a peg that runs in a slot in the cover.

When the spring washers are compressed they actuate the limit switch on which breaks the hold circuit of the motor and the current supply to the motor is shut of. It is also possible to connect the closing contact of the limit switch to an indicating lamp. The limit switch has an alternating facilitator. It is produced by Tele mechanics and has the designation XCK M1 D1O.


When the overload protection is mounted between the gear housing and a lug on the machine it should not be installed too tight. There should be a small movement allowed at the ends.


The overload protection unit is delivered with a factory tested and set breaking force value. If the overload protection has to be adjusted this should preferably be done at our factory. The breaking force is adjusted by changing the position of the adjustable cover by use of the special tool that matches the hole in the cover. The breaking force at different preload settings is shown in the diagrams opposite.


The overload protection unit is delivered with the tension bar filled with grease and does normally not require any maintenance. Function test should be carried out once a year to ensure the correct setting of the breaking force. The movement of the tension bar should not be affected by external factors such as corrosion or similar. The electrical installation must be correctly connected in order to ensure the overload protection unit works properly. A regular inspection of the electrical system is also recommended.

Type L L1 L2 D d I G S Braking force kp
R1″ 155 40 20 34 12,2 12 M12 0 40-600
R2″ 300 60 45 60 20,2 20 M24 2 200-2500
R3″ 311 40 50 88 30,2 30 M30 7 1250-7000