The Switch-Head Dynamometer is an electro-mechanical instrument for measuring tractive force and operating control circuits. It is suitable for use in tension control of belt conveyors, load control of lifts, lifting equipment, ski lifts, haulages and batch control.

The pull rod movement (approx. 10 mm) operates the scale drum through a square thread stem. By the use of a microswitch directly influenced by the pull rod, the dynamometer gives an electrical switching function at a previously set value.

The power absorbing element consists of an arrangement of specially made Belleville type spring washers of a spring steel alloy, so designed as to be entirely free from wear. The arrangement also ensures that the spring washers cannot be overloaded.

Dynamometers up to 3000 kg capacity can be equipped with 1-3 switch functions. Sizes above 5000 kg and larger are available with 1-5 switch functions. The electrical connections are made in the terminal box to a numbered connection block.

The instruments are fully pressure tight and each instrument is pressure tested. No leakage is permitted. The external surfaces are zinc plated with clear chromate passivation. If the instruments are to be used in a very corrosive atmosphere, they can be polyester lacquered.

Safety factor 5:1. (Guaranteed to withstand a load of 5 times full scale reading before rupture.)

The instruments may be overloaded by 100% without impairing the accuracy. The sizes 500-25000 kg have drop-forged steel brackets (SS 2174), giving a guaranteed impact resistance to -20ºC.

The O-ring of the pull rod is protected by a neoprene rubber membrane. On instantaneous unloading, e.g., breaking test, the return movement of the pull rod is retarded by a specially designed spring washer (shock resisting disc spring).

1. Loosen the two Allen screws on the microswitch slide. (N.B.) Do not remove them completely!)
2. Connect a suitable instrument to the respective terminals in the terminal box that will indicate when the circuit has been closed or broken.
3. Apply a load to the dynamometer until the scale drum indicates the value required.
4. Move the microswitch slide downwards to its lowest position and then upwards until the indicating instrument shows a circuit change.
5. Retighten the Allen screws firmly and slacken off the load. Screws not properly tightened may allow moisture to leak inside and cause corrosion.
6. Reapply the load and check that the switch setting has not been disturbed when retightening the Allen screws.
7. Repeat for each switch.

The contact function is an electrical switching arrangement with a microswitch that may make or break circuits at set load values on the dynamometer. The Switch-Head Dynamometer with one or two microswitches is available with alternative contact function for each microswitch.

When three, four or five microswitches are used, only one breaking contact function for each microswitch is used as standard. If other contact functions are required, details must be given when ordering.

When the Dynamometer is used in devices where the safety is of utmost importance, breaking function should always be used.

The microswitch has self-cleaning, gold-plated silver contacts, which makes it suitable for low power (below 10 V and/or 60 mA). The switch value can be changed at any time, see "Method of Setting" above.

Scale: White-lacquered with black graduation.

The dynamometer can be graduated in kg, N, lb. etc.

The electrical connections are made in the terminal box to a numbered connection block. (Is also available on the inside of the terminal box.)

All instruments are delivered without storage case.

The dynamometers are equipped with brass shields.

Please Note: The Craneweigher is also available with switch-head.