Limit Switches

Application :
These Controllers are suitable for operation of Heavy Duty EOT Cranes and Rolling Mill Drives on Power and Control Circuits upto 500 VAC 50 cycles at 40A continuous current. when used as Master Controller, the maximum permissible frequency of operation is 1000 switching per hour. V\when used as Cam Controllers, the maximum permissible frequency of operation at rated current is 720 operation per hour.

Basic Specification:
Heavy Duty. Reversing Air Break Cam Controller / Masters with joystick operating handle Maximum working voltage 500V A, C. 3 phase 50 cycles. Maximum continuous current 40 amps maximum number of notches 6 on either side. A greater number of notches can be provided for special purpose controllers if so required.

Construction:
The housing of controllers is made of heavy gauge sheets steel suitably reinforced to give exceptional rigidity which is essential for satisfactory operation. The Cam Shaft is mounted in the housing, on moulded bushes (bearing) of synthetic material fixed to the front and rear Walls. These bearings do not require any lubrication whatsoever. The Cams themselves are moulded from the highest quality malemine and are accurately cut to correspond to the switching sequence. The Cams have an exceptionally long life.

Switching Element :
The body of the switching elements is made of high grade Malemine which is specially suited for heavy duty. The material is non-tracking and is capable of withstanding heavy arcing. The contacts themselves are made from high grade silver cadmium alloy which are continuously rated upto 40 amps. These contacts can interrupt a current of 70 amps at 500V a/c. when fitted with are barriers between adjacent contacts.

Switching Capacity:
The same switching elements are used in both. Cam Controllers and Master Controllers. The switching capacity of the contacts when used for Master Controller operation is 15 amps at 440 ale on highly inductive loads and 2.5 amps on 220V DC when handling inductive loads. These switching capacities are fal' in excess of those actually required in practice, as such, replacement of Contacts for Master Controllers may not be necessary.

Limit Switches
Two way Shunt Limit Switch is also to prevent over travel or over traverse. The Limit Switch is fitted with 2 numbers of silver cadmium bimetal (cladcon) tipped contacts which remain normally closed and supply power to the contactor coil in control panel. When the lever is moved over a projecting member fixed at a predetermined position on either side of the gantry, the power supply to the contactor coil is cut off. The contacts are rated for 10 amps, at 440 Volts A. C. 50 cycles supply system.

Construction
The housing of the limit switches is made of heavy gauge sheet steel suitably reinforced to give exceptional rigidity which is essential for satisfactory operation. The shaft is mounted in the housing on moulded bushes (bearing) of synthetic material fixed to the front and rear walls. These bearing do not require any lubrication whatsoever. The cams themselves are moulded from the highest quality malemine and are accurately cut to correspond to the switching sequence. The Cams have an exceptionally long life.

Two Way Series Switch Type
Limit Switch to prevent over travel or travels will normally remain closed and will cut off power and stop the motion only when it reaches a pre-determined position, when the lever is moved over projecting member fixed to the Gantry. The Limit Switch is of series type fitted with two sets of contacts which cut off two phases. of the motor in either direction and are suitable for 440 Volts A. C. 50 cycles supply. Limit Switch Contacts are automatically reset when the lever returns to 'Zero' position due to spring action. Contacts are rated for 60 Amps. The side covers are of cast Iron. The top and bottom covers are Sheet Steel. The Lever is of steel fitted with roller.

Geared Limit Switch For Hoist Drive
Heavy Duty type Limit Switches have a gear ratio of 48 : 1 (36: 1 or any desired ratio) and contact rating 600 Watts '\,.../ inductive at 600 Volts A. C. 50 cycles with keywayed shaft extension suitable for flexible coupling. The Limited Switch will be dustproof and weather proof. The Limit Switch will be rotary type suitable for left I right hand operation. The limit Switch has two contacts. One contact cuts off power supply to the coil circuit of the hoist or forward contactor, and the other contact cuts off power to the Down or Reverse contactor. The contacts are automatically rest in the reverse direction. The Limit Switch shaft can be directly coupled to the winch drum or chain or gear drive according to individual requirement.

Hoist Limit Switch
Limit Switch to prevent over hoisting, will remain normally 'ON' due to the weight connected to the lever. When the Snatch block reaches the highest position the weight pulling the lever down is moved up on the snatch block. The Lever is therefore released and the two contacts cut-off two phases of the motors thereby stopping the hosting Motion. The Limit Switch automatically resets when the snatch block is lowered. The Limit Switch is suitable for 440 volt A. C. 50 cycles supply system. This Limit Switch is of series type and the contacts are rated for 60 amps.