Use in Inclined Belt Conveyors / Bucket Elevators etc.

The Backstops / Holdbacks are extensively used in Inclined Belt Conveyors / Bucket Elevators etc. to arrest the rolling back of the machine in case of power shut down or sudden stoppage of the equipment due to any reason, thereby avoiding the material being transported to fall-off the machine thus avoiding accidents.

Use in Pumps, Industrial Fans, Blowers, Compressors

The Backstops / Holdbacks are also extensively used in Pumps, Industrial Fans, Blowers and Compressors to prevent the startup in the wrong direction as well as to arrest the reverse operation in case the impellers rotate in the opposite direction for any reason which may lead to undesired situation and accidents.
The backstops are generally fitted on to the extended shaft of the motor or gearbox or in some cases on the main driving shaft of the machine.

We offer the units in following types:

• Roller Type Backstops
• Sprag Type Backstops

The type of backstop to be selected depends on various factors like application, speed of operation, ambient temperature, location, space availability, support system etc.

Roller Type Backstops

Roller Type Backstops essentially consists of two concentric cylindrical races, with inner race having Ramps on the outer surface where Rollers are located. The rollers are kept in place with springs and plungers so that energized rollers are in permanent contact with the inner surface of the outer race and the surface of the ramp. The backstop is provided with two ball bearings to ensure concentrically between inner& outer race and to combat radial and axial loads.

The inner race having bore & keyway is mounted on the rotating shaft (extended shaft of the gearbox) or machine shaft.
The outer race is fixed and locked to the body of the gearbox or the machine structure. The fixing arrangement can be Torque Arm or Flange Bolting.

The Roller-Ramp action allows the shaft to rotate in one direction only. In case of reversal of rotation, the wedging action of the roller and ramp comes into play and the reverse rotation is arrested instantaneously.

Sprag Type Backstops (Standard Design)

The unit essentially consists of two concentric rings (races) with the inner ring mounted on the shaft rotating with sprag cage (fixed with pins and circlips) in freewheeling action. The specially contoured sprags are individually spring loaded and are guided in the cage. The outer race is fixed and locked to the body of the gearbox or the machine structure.

Sprag Type Backstops (Centrifugal Lift-off type)

The popular backstop is Centrifugal Lift-off type which has emerged as the most reliable and economical solution to the needs in industry.

The unit essentially consists of two concentric rings (races 1 & 2)), with the inner ring mounted on the shaft rotating with sprag cage (3, fixed with pins and circlips) in freewheeling action. The specially contoured sprags (4) are individually spring loaded and are guided in the cage. The outer race is fixed and locked to the body of the gearbox or the machine structure.

The special feature of this type is when speed reaches lift-off stage; the sprags disengage completely and rotate free without any contact or friction with the outer race thus making the unit free of wear.

• Power in K.W. / H.P. to be transmitted

• Operating speed of the shaft on which the backstop is to be mounted in R.P.M.

• Shaft Dia. x Length of the shaft on which the backstop is to be mounted

• Application or driven machine

• Fixing Location i.e. body of the gearbox or the machine structure

• Fixing arrangement i.e. Torque Arm or Flange Bolting

• Space limitations if any, (In case of replacement of existing units)
  

• Prime Mover: Motor, Engine, Turbine etc.

• Rated Power & Speed of Prime Mover

• Duty: Number of working hours/day

• Installation: Horizontal, Vertical or Inclined
  

• Ambient Temperature

• Number of starts / stops per hour
  

• Any other special condition.

The Shrink Disc is a key-less hub-shaft connection device mounted on the outer surface of the hub which exerts external clamping force on the hub, thus establishing mechanical shrinking force between solid shaft and hub.

This type of connection can transmit axial loads, high torque and reversing loads.

The Shrink Disc basically comprises of two Thrust Rings (2&3), a solid double tapered inner ring (1) and a seal ring.

When the screws (4) are tightened, the pulling of both Thrust Rings takes place which exerts radial forces on the taper ring, which in turn clamps the hub resulting in gripping the solid shaft.

The Shaft hub connection can be released by loosening the screws.

Information Required for Selection:

• Diameter of Solid Shaft

• KW/HP transmitted

• Speed of operation in RPM.

• Application

• Grade of Shaft material

• Grade of Hub material

• Ambient Temperature

The locking element device is a key-less hub-shaft connection installed between outer surface of solid shaft and inner surface of hub.

This type of connection can transmit axial loads,high torque and reversing loads.The locking elements can be used in series to transmit higher torques and axial loads.

The operating principle is the gripping of the solid shaft by inner double taper ring (3) and gripping of hub by outer double taper ring (2). When the screws (9) are tightened, the inner ring clamps the shaft and simultaneously outer ring clamps the hub.

The shaft hub connection can be released  by loosening the screws.

Information Required for Selection:

• Diameter of Solid Shaft

• KW/HP transmitted

• Speed of operation in RPM.

• Application

• Grade of Shaft material

• Grade of Hub material

• Ambient Temperature