New motorised version of torque-arm shaft-mounted speed reducer

Paul Boughton

A new motorised version of the Dodge torque-arm shaft-mounted speed reducer from Baldor Electric Company will make its European debut at Hillhead 2010. Baldor claims that this provides a breakthrough in compact and robust speed reduction, and complements Dodge's renowned belt-driven speed reducers.
The Dodge Motorized Torque-Arm II shaft-mounted speed reducer is a right-angle gearbox with an IEC flanged motor interface, specified for use with two-pole or four-pole motors. A choice of 12 helical gear reduction ratios and three case sizes enables the unit to deliver a wide range of speed reductions from 18:1 to 75:1 for class 2 applications from 1.5-55kW, with very high efficiencies of up to around 95 per cent.
Furthermore, the Motorized Torque-Arm II (MTA) has been optimised for robustness, with Baldor saying it offers considerable advantages over comparable gearboxes designed in accordance with European design practices. The reducer is rated to meet the 6010 AGMA (American Gear Manufacturers Association) standard, which specifies a 5000-hour bearing life, which is approximately twice as long as comparable DIN design specifications.
Other reliability-enhancing features include the use of heavy-duty tapered roller bearings instead of ball bearings, and a novel input pinion shaft with straddle-mounted bearings on both the motor and gearing sides. This latter construction combats any overhang stress resulting from a poorly mounted motor, and additionally allows the gearbox to be offered in a sealed form that protects the gears against any contaminants during any installation or maintenance operations at the motor input.
Premium HNBR (hydrogenated nitrile butadiene rubber) seals are fitted as standard for extra protection, and the MTA is designed to be used with Dodge patented twin tapered bushings that provide a sturdy, concentric grip on the driven shaft on both sides of the reducer. This eliminates the wobble and fretting corrosion normally associated with single-bushed shaft-mounted reducers.
Charles Gubser of Baldor Electric Company states: "This is the first AGMA-rated right-angle motorised torque arm reducer on the market we believe, and it provides an interesting alternative to conventional gearboxes wherever space is at a premium, and robustness is critical. We expect it to be of considerable interest to OEMs in machinery sectors including conveyors, and mixing and milling equipment dealing with harsh materials and in heavy-duty bulk handling applications."
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