32. Hydraulic clutch

a.   Principle of the hydraulic clutch

1- Centrifugal pump          4- Actuating shaft

2- Hydraulic turbine          5- Receiving shaft

3- Cover

b.  Feature

-When the hydraulic clutch is working stably, torque on the receiving shaft is not changed.

-Centrifugal pump and hydraulic turbine have the same dimension.

-High transmission efficiency.

c. Transmission efficiency of the hydraulic clutch

When working, the clutch generates hydraulic loss; so a little part of the main engine power is lost. That energy is transformed into heat therefore raising the temperature of the liquid. The loss of power is performed by transmission efficiency of the hydraulic clutch:

ηLH=N2/N1 (%)

Because the torque is not changed when transmitting, M1 = M2. Therefore:

ηLH = N2/N1 =M2.n2/M1.n1 =n2/n1 (%)

Where: N1, M1 - Power, torque on the pump shaft.

N2, M2 - Power, torque on the turbine shaft.

n1, n2- Revolutions of the pump shaft and the turbine shaft. 

When the hydraulic clutch is working, the revolutions of the pump and the turbine are not same, it creates a slip:

S= (n1-n2)/n1 =1-ηLh (%)

In fact S is about (2 ¸ 4)%.