MULTI PLATE CLUTCH

The clutch having more than three discs is referred as multi disc clutch or multi plate clutch. It is similar to single plate clutch but has more number of frictional and metallic plates. Due to the increase in the numbers of plates (friction) the frictional surface in contact is also increased which increases the capacity of the clutch to transmit the some torque the diameter of the plate clutch. Hence the clutches are mostly commonly in two wheelers and three wheelers due to compact in size. It is used in heavy duty transmission system for transmitting higher torque. (For example torque transmission in heavy earth moving equipments) and power take off (P. T. O.) transmission in tractors.

 

Construction: Construction of multi plate clutches is similar to single plate clutch except the arrangement of number of friction plates and metal plates. It consists of inner drum which is referred to clutch shaft and has a number of plates splined to the outer surface. Another drum is coupled to fly wheel and carries a number of plates splined to it inner surface. The plates are arranged in alternate manners. The plates can revolve with the drum as well as it can slide axially. A spring keeps the outer and inner plates pressed together, so that the driving members transmit the power to the driven member. The clutches can be disengaged by pulling the inner drum against the spring force.

      Multi plate clutch can be dry type or wet type. The clutch is partially filled with oil. The coefficient of friction in oil varies from 0.07 to 0.17 of asbestos based fabrics.

1. The oil acts as cushioning  medium to provide smooth engagement and disengagement
2. The oil also carries the heat dissipated by the clutch due to friction. This reduces operations temperature and increases the left of the clutch plates.
3. The oil acts as lubricant and reduces axial thrust lost due to bending on splines.

The major disadvantage is the reduction in coefficient of friction when immersed in oil. It can be compensated by using high operating pressure of different friction material. Generally cork inserted multi plate clutches are used in wet clutches. In wet clutches the fluid under pressure is fed along the shaft.