Product Description:

The 1MR375B-A170/S026 is a rotor component built by Bosch Rexroth Indramat for the 1MB High-Speed Asynchronous Motors series. As the rotating element in a frameless spindle motor, it is shrink-fitted into the machine tool spindle sleeve and works with a stationary stator to produce torque. This arrangement supports compact, high-speed drives that position cutting tools or workpieces with repeatable accuracy in automated machining centers. Because the rotor is installed directly into the spindle structure, the drive layout does not require a separate motor housing or a shaft coupling.

With a frame size of 375, the rotor has an outside diameter of 273.7 mm that aligns with the matching stator bore. Its central bore measures 170 mm in diameter and extends 322 mm along the shaft axis, using a 170 H6/s6 primary fit for the stepped interference seat. The rated speed limit is 2400 rpm, and the rotor uses three pole pairs with a balancing ring that screws into the M10 thread at the nose. Hydraulic oil can be injected through the M6 pressure-oil port during mounting to reduce assembly force on the interference surfaces. Motor length code B identifies this dimensional package, and the rotor has an inertia of 1.39 kg·m², which supports stable acceleration and helps limit vibration during machining.

The rotating package weighs 106 kg, which adds mass to the spindle assembly during sustained cutting duty. The overall length is 430 mm, but the spindle assembly must provide at least 437 mm of internal space so the stator laminations clear the shaft ends. Within that available space, the stepped spindle seat occupies 325 mm and interfaces with the bearing and locknut arrangement used in this series. The unthreaded rear shoulder accepts the M10 balancing hardware after final grinding, and the polarity mark from the three pole pairs remains accessible for encoder alignment. Adequate internal clearance is needed so adjacent spindle components can be fitted without contact during operation.