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>>> Components
The hydrostatic slip drive consists of the following components:
see table IV

The slow speed high torque hydraulic scroll drive motor (R) ROTODIFF, is a rotating unit.
The Pump Unit (P), mounted on the floor, near Rotodiff.
A control system either (H) hydrostatic or (E) electronic control.

>>> The hydraulic scroll drive motor ROTODIFF
see table l

>>>> General:
The Rotodiff housing is directly bolted to the centrifuge bowl and the drive shaft is joined to the centrifuge scroll like a normal gear box. The Rotodiff mounted on the centrifuge rotor and, together with a Pump unit, comprises the complete drive system.
The Rotodiff (R) is a slow speed, high torque hydraulic motor with a constant displacement. The housing is flanged to the decanter bowl, and the Rotor (R6) drives the decanter scroll (C1). In this way, the scroll is driven at an adjustable differential speed, independently of the bowl speed. The high pressure hydraulic oil (red path) is brought from the stationary part (R3), to the rotating part of the motor (R6), by means of the transfer seal (R2). The unpressurized hydraulic oil (blue path), flows back to the pump unit over the stationary part (R3).

>>>> Working principal of the hydraulic motor
see table II

The hydraulic motor is a positive displacement radial piston motor. The cam (R4) transmits the force exerted by the piston rollers (R8) through pressure from the pistons (R7). The tangential component of this force produces the rotation of the rotor (R6). The pistons in the cylinder are subject to fluid under pressure via the distributor (R5) which is mechanically linked to the cam. The cylinders are thus alternately connected to the high pressure of the hydraulic feed system (working stroke; red path) and the low pressure of the casing (return stroke; blue path).

>>>> Working principal of the transfer seal
see table II

This element is critical for the function of the hydraulic motor. It has the ensure a very low leakage rate under highest pressures, and must have a adequate passage for the high pressure oil flow as well as extremely low friction loss. A ball cone (R9) is placed on the rotating part eccentrically, and is connected via a double cone floating eccentric ring (R10) to the stationary, compensation cap (R11). The rotating ball cone and stationary compensation cap (parts R9 + R11) cause a tumbling motion of the floating eccentric ring, which continually laps and polishes the contracting surfaces. A considerable axial force is generated between the stationary and the rotating part. This axial force is contained by the two angular ball bearings (R12).


Table l

Table ll

Table IV