Ultra-precise gearhead for servos and steppers

An Inmoco product story

Edited by the Engineeringtalk editorial team Mar 2, 2001

Intelligent Motion Control is extending the output torques of servo and stepper motors to class leading levels with the introduction of the new Ultratrue 22 from Thomson Micron.

Intelligent Motion Control is extending the output torques of servo and stepper motors to class leading levels with the introduction of the new Ultratrue 22 from Thomson Micron.

The in-line Ultratrue 22 combines True Planetary gearing, revolutionary face gear technology, exceptional stiffness and torsional rigidity in a package that delivers ultra-smooth and accurate operation and a torque capacity, which at over of over 5,524Nm, is the highest in its class.

The Ultratrue 22 gearhead is the latest introduction to a comprehensive range that includes both in-line and 90o gearheads.

It offers thirteen ratios from 4:1 through 100:1 and features backlash as low as 4 arc minutes.

The ability of the Ultratrue 22 to deliver large amounts of torque owes much to its high strength and exceptional torsional rigidity.

These are the result of a manufacturing design that specifies a robust 75mm output shaft and machines the output housing and the helical internal gear from a single piece of high strength steel.

The same design also retains True Planetary gearing technology, and the benefits it provides in terms of high precision, long life and efficiency (typically 90%) that derive from multiple gears sharing a load.

The Ultratrue's True Planetary arrangement, with three gears in constant mesh, allows the load to be equally shared over the planet gears.

As each gear carries one third of the torque the resultant forces are cancelled out to yield a resultant load equal to zero.

When compared to old style, conventional spur or hybrid gearheads (combination of spur and planetary), True Planetary gearing facilitates motor bearing life, which is several hundred times longer.

To the user this means reduced downtime and lower production costs.

Users of the Ultratrue 22 also benefit from the precision gearhead's ability to deliver ultra smooth and quiet speed reduction.

These result from the combination of Helical crowned planet gears and Thomson's high-tech Powertrue face gear technology.

The latter also offers additional benefits in terms of eliminating errors due to backlash.

With Powertrue technology the gear meshes with a standard involute pinion.

As there is only one axis to adjust, that being the face gear into the pinion, the backlash and contact pattern can be easily verified.

This design eliminates the errors associated with measuring and shimming of spiral bevel systems by direct adjustment of the gear face during the assembly process.

Mounting of the Ultratrue 22 to a motor couldn't be easier with Thomson's novel Redimount system.

The error-free mounting system allows the integration of the gearhead to any servo or stepper motor with high reliability and does not require a technician or an experienced engineer to accomplish the task.

The Redimount system incorporates the pinion directly into the gearhead.

It is supported on its own bearing system.

By means of a split collar hub that is integral to the pinion bearing system the motor is positioned concentrically on the pinion axis.

The variety of motor shaft diameters that exist are accommodated by a split sleeve that is housed in the bore of the hub.

The sleeve is retained axially and rotationally by means of an o-ring in the hub to simplify mounting.

After positioning the motor into the hub and assuring that motor and gearbox flanges are in contact, a pair of screws in the hub are lightly secured.

The four bolts, which connect motor and gearbox flanges, are tightened and the hub screws are secured to the proper torque level.

With their lubricated- for- life construction the Ultratrue 22 gearheads are essentially fit-and-forget units.

Their high levels of precision and robustness mean that they are suitable for a wide range of motion tasks in industry sectors such as packaging, machine tools, materials handling, injection moulding, semiconductor manufacturing, food processing, paper and pulp manufacturing, metal forming, medical diagnostics, printing, textiles, robotics, optical positioning, and many more.