Lever Limit Switch are used for heavy duty E.O.T. Cranes, Wagon shunting devices etc., to prevent over travelling or over traversing on power and control circuit up to 500 volts A.C. 50 cycles / second and 40 amps current rating.
The Crane Control Equipments make Lever Limit Switch normally remains closed and cuts off power to stop the motor of the particulars motion.
- The lever Limit switch operates when its lever reaches its pre-determined position and the lever is moved over a projecting member fixed on the Girder.
- The Limit Switch contacts are automatically reset when the lever returns to zero position due to spring action.
- The Lever Limit Switch is made in IP-41 as well as in IP-54 enclosure .
- In case of IP 41 enclosure the housing is made from suitably reinforced sheet steel where as in case of IP-54, the cover is of Cast Aluminum. Also in this case the base and cover have machined surface to protect the Limit Switch against dust.
- The cam shaft on which the cams are fitted is mounted in the housing on moulded bushes of synthetic material which are fixed to the front and rear walls by means of screws.
- The Cams which are fitted on the cam shaft are moulded from the highest quality synthetic material and are accurately cut to correspond to the switching sequence desired.
- The contacts have a maximum continuous Current capacity of 40 amps AC.
- The contact tips are made of high grade Silver Cadmium Oxide alloy.
- When used for Series operation[ up to 40 Amps maximum], the Contacts are suitable for 720 operations per hour and in case of Shunt operation [ for Control Circuit ] , the Contacts are suitable for 1200 operation per hour.
- The same Contacts can be used in Series as well as in Shunt configurations
- The switching capacity of the Contacts when used for Shunt operation is 15 amps at 400 Volts, AC on highly inductive load and 2.5 amps at 220 Volts DC .
- These switching capacities in fact are far in excess of what is actually required in practise and hence replacement of Contacts for Shunt may not be necessary for a long time.
- The body of the Contacts is made of high grade Melamine which is specifically suited for heavy duty operation .The material is non – tracking and is capable of with standing heavy arcing.