New Motorized Torque Arm Achieves Longer Life

Withthree million Torque-Arm speed reducers already working in the field, new DodgeTorque-Arm designs are expanding the available options by using a motorized,beltless version of the product for rugged, harsh-duty applications. And now aredesign of the Motorized Torque Arm (MTA) is targeting applications from 3 to75 hp where customers were forced to put a traditional gear-motor-drive packageinto a harsh environment and didn't achieve long life.

"In 2007, Baldor introducedtwo sizes of the Motorized Torque-Arm(MTA) to test the market. The current release is a completeredesign which provides three sizes and higher torques up to 65,000 pound inch,"says Rick Stewart, product manager for Torque Arm & RenewalParts at Baldor Electric. "The MTA has the same ratings, bore sizes andaccessories as the Torque Arm II, but also provides a direct drive solution forharsh-duty environments,"

The Torque-Arm brand started with Dodge in1949 and, over the last 60 years, the company has developed differentvariations and innovations. It is mostly used in harsh-duty environments suchas cement, aggregate and grain handling.

The MTA is a beltless version of theTorque-Arm II product and uses the exact same technology, gear geometry,features and sealing systems. It is in full compliance with American GearManufacturers Assn. (AGMA) guidelines.

"AGMA has developed engineering criteria forgear life expectancy, minimum bearing life, and overload capacities that arerequired for engineers to use when rating a product for applying the AGMA stamp,"says Stewart. "Only a handful of companies follow the guidelines and no othergearing manufacturer that we know of follows the guidelines for a gear-motor orNEMA C-face right angle product."

The unit is a complete drop-inreplacement and interchangeable with the current Torque Arm product. It has thesame torque ratings and uses the same accessories such as bushings, so thatfrom an engineering perspective the motorized version provides a drop-inbeltless solution.

The new MTA product offers a dualseal system featuring both an oil seal and dust seal which is identical to the Torque-ArmII. It exclusively uses tapered roller bearings, and doesn't use ball bearingsor light-duty bearing support mechanisms found in competitive right-angle products.

The product design also uses center "straddlemount" input pinion to provide maximum torque transmission. Stewart says that almostall gear motors use an overhung shank pinion, which is lower cost but less resilient when it comes to intenseshock loads or overload conditions which the straddle mount design handles moreeffectively.

Another unique feature is an integralbackstop. Most gear motors have a non-reversing clutch mechanism inside of thereducer to keep the unit from back driving. If the application is an inclinebelt conveyor which stops, for example, the user doesn't want the load to movebackward down the conveyor. With other gear motors, that requirement needs tobe specified upfront as a required feature along with the direction of rotation.With a motorized torque arm, the backstop can be installed in the field, andusers can also reverse the direction of the backstop in the field.

"The motorized torque arm is also amodern design relative to lubrication capabilities," says Stewart. "Both theTorque Arm II and MTA are fully compatible with most synthetic lubricants onthe market, and can also handle extreme pressure additives. It is very rare fora gear manufacturer to be able to use synthetics and EP additives withoutaffecting the performance of the sealing system or backstop."

Because the motorized design usesTorque Arm II accessories, it can be easily applied to a screw conveyor drive,mixer drive or a traditional shaft mounted conveyor drive. The unit uses thesame bushings, both metric and imperial, screw conveyor adapter and the sameexact accessories that are readily available all around the world. Themotorized torque arm is designed for NEMA motors, as well as metric IEC motorswhich means it can fit on both imperial and metric shafts.

For the connection between a motorand gear reducer, quill mounts are commonly used in worm gear boxes to drivelight continuous loads. A slightly more robust connection is called a clampcollar which is used for material handling in warehouses where there ismoderate loads and active start/stopping.

The most robust connection is a three-piececoupling method which features a rubberized coupling mechanism between thegearbox and the motor to absorb heavy shock loads. The MTA is designed withthree-piece couplings throughout the product, and offers a rubberized elementjaw style coupling that is designed specifically for high shock environments.

"We see the new MTA going intosimilar applications where Torque Arm is used today but where a direct drive isnow required. The MTA gives the engineer an option to use a beltless solutionwith an inverter duty motor or premium efficient motor in very harsh environmentsand offer a longer life, heavy-duty product," says Stewart. "For an engineer tomove to an inverter drive motor or premium efficient solution, they werepreviously forced to go with a ball bearing unit with a light-duty sealingsystem that was designed for traditional unit-handling applications."

CON-E-CO, a manufacturer of stationaryand portable concrete equipment plants, has been using Torque Arms for many years.Due to space restrictions on their portable concrete plants, they have nowstandardized on the MTA.

The design of the MTA saves overheadspace, so when a folding conveyor is being collapsed into position to drivedown the highway, the gearbox motor fits right into the conveyor section. Whenthe conveyor unit is extended in the field, the MTA rotates up with theconveyor and doesn't require additional space normally used for the v-beltdrivenunits where the motor mounts on top the reducer. CON-E-CO also still utilizes theTorque Arm II product but have specific applications where the MTA gives themall of the ratings and sealing performance of the industry-leading Torque-Armproduct line.

"Most customers have similar needs where 80to 90 percent of their needs are addressed by the belted Torque Arm but thereare some applications with a unique user specification or space constraintsthat require a direct drive," says Stewart.

During a market survey for theproduct, Baldor identified a target market for equipment where there are eitherspace constraints or international requirements. In portable equipment wherethere is folding, plus hauling and width limitations, the MTA is much narrowerthan a traditional gearbox in that torque class. And many internationalcustomers often don't want a v-belt on their product or an integral gearmotorbecause of power consumption.

Globalization is starting to movethe market toward direct drive solutions, a trend that is starting to move intothe U.S. primarily due to mergers and acquisitions.

The v-belt does provide the reducerand entire path, even the customer's equipment, some protection from uncertainshock loads because the v-belt will slip. One of the reasons it is popular is itsmechanical shock resistance, plus it provides a low-cost way to change speeds. V-beltshave been around for years but we are seeing some trends toward the beltlessproduct even though they are no companies with a severe duty beltless productin this size range.

Stewart says the MTA product is alogical move for Baldor-Dodge to provide longer life and durability forauxiliary or secondary drives. Most primary drives will continue to betraditional shaft mounted units, with torque requirements as high as 500,000 lbinch and drives in the 1 to 200 hp range. The motorized drives are focused onrequirements for 3 to 75 hp range where there is strong demand.