To address the need among mobile-equipment builders for fluid-power drives that have higher power density, Bosch Rexroth is expanding its range of direct drives with the new MCR-T radial-piston motor in frame size 10. The motors are for use in compact tracked loaders and other tracked vehicles. The newly designed unit is approximately 20% shorter than conventional radial-piston motors on the market and offers around 10% higher starting torque for more tractive force. And to improve efficiency, especially when machines must move long distances, the MCR-T units also allow for high travel speeds at low diesel-engine speeds.
The compact design complements the MCR-T family of motors in frame sizes 5 and 6. To shorten the overall length and let the unit completely fit in the track width of compact loaders, Rexroth engineers integrated the fail-safe, multi-disc holding brake into the outboard portion of the motor housing.
Starting torque has increased by 10% thanks to improved hydrostatic pressure bearings between the piston, roller and cam lobes in the motor. And better load distribution lets the MCR-T withstand higher radial forces. The optimized drive-shaft position permits the use of a simpler sprocket than seen in conventional radial-piston motors. Larger bearings that are flushed with case oil increase service life up to 30%. An integrated flushing valve supports oil cooling when used in closed hydraulic circuits, which can also lengthen service life and contribute to lower the total cost of ownership of mobile machines.
MCR-T radial piston motors are designed for continuous high rotational speeds so that compact tracked loaders can efficiently travel longer distances. Via a control valve integrated in the motor, the operator can gently shift between travel speeds with the soft-shift mode operating in both directions. The motor then runs with lower displacement, reducing oil flow in the circuit. Thus, the direct-drive MCR-T provides greater efficiency and lower noise than typical gearbox-based systems.
MCR-T motors operate with a differential pressure of up to 400 bar (5,880 psi) and the largest version has an output torque of up to 8,500 Nm. Displacement of the series ranges from 620 to 1,340 ccm.