MCR Series Rexroth Walking Hydromotor

MCR Series Rexroth Walking Hydromotor

Series 3X
Size 160 to 400
Differential pressure up to 450 bar
Torque output up to 2300 Nm
Speed up to 875 rpm
Open and closed circuits

MCR3A325A45Z33B2M1L01F12SO522N 

Hydraulic motors type MCR are radial piston motors with a rotating shaft. Construction Two part housing (1, 2), rotary group (3, 4), cam (5), drive shaft
(6) and flow distributor (7) Transmission The cylinder block (4) is connected to the shaft (6) by means of splines. The pistons (3) are arranged radially in the cylinder block (4) and make contact with the cam (5) via rollers (8).

The number of working and return strokes corresponds to the number of lobes on the cam x number of pistons (8). Flow paths The cylinder chambers (E) are connected to ports A and B via the axial bores and the annular passages (D).

Bearings
Tapered roller bearings capable of transmitting high axial and radial forces are fitted as standard, except on Hydrobase motors.
Freewheeling
In certain applications there may be a requirement to freewheel the motor. This may be achieved by connecting ports A and B to zero pressure and simultaneously applying a pressure of 2 bar to the housing through port L. In this condition, the pistons are forced into the cylinder block which forces the rollers to lose contact with the cam thus allowing free rotation of the shaft.

Two speed operation (2W)
In mobile applications where vehicles are required to operate at high speed with low motor loads, the motor can be switched to a low-torque and high-speed mode. This is achieved by operating an integrated valve which directs hydraulic fluid to only one half of the motor while continuously re-circulating the fluid in the other half. This “reduced displacement” mode reduces the flow required for a given speed and gives the potential for cost and efficiency improvements. The motor maximum speed remains unchanged. Rexroth has developed a special spool valve to allow smooth switching to reduced displacement whilst on the move. This is known as “soft-shift” and is a standard feature of 2W motors. The spool valve requires either an additional sequence valve or electro-proportional control to operate in “soft-shift” mode.

Flushing valve
In a closed circuit, the same hydraulic fluid continuously flows between the pump and the motor. This could therefore lead to overheating of the hydraulic fluid. The function of the flushing valve option is to replace hydraulic fluid in the closed circuit with that from the reservoir. When the hydraulic motor is operated under load, either in the clockwise or anti-clockwise direction, the flushing valve opens and takes a fixed flow of fluid through an orifice from the low pressure side of the circuit. This flow is then fed to the motor housing and back to the reservoir normally via a cooler. In order to
charge the low pressure side of the circuit, cool fluid is drawn from the reservoir by the boost pump and is fed to the pump inlet through the check valve. Thus the flushing valve ensures a continuous renewal and cooling of the hydraulic fluid. The flushing feature incorporates a relief valve which is used to maintain a minimum boost pressure and operates at a standard setting of 14 bar (other options available on request). Different orifice sizes may be used to select varying flows of flushing fluid. The following table gives flushing rate values based on a boost / charge pressure of 25 bar.

• Smooth running at very low speeds
• High volumetric and mechanical efficiencies
• Bi-directional
• Wheel flange with wheel studs
• Available with parking brake (multi-disk) or dynamic brake (drum)
• Available with bi-directional two speed function
• High radial forces permitted on drive shaft
• Compact robust construction
• Freewheeling possible
• Sealed tapered roller bearings
• High reliability
• Low maintenance
• Low operating noise