Dodge Torque-Arm II Shaft-Mount Gear Reducer

Shaft-mount gear reducer with twin-tapered bushings

The Dodge Torque-Arm II (TA II) is a helical shaft-mount speed reducer. The reducer slides directly onto the driven shaft, a torque arm fixed to the gear case and the support structure takes the reaction, and the drive needs no coupling, base or foundation alignment. Dodge says Torque-Arm products have been in service since 1949 with more than three million units installed, and the TA II adds a patented harsh-duty sealing system, twin-tapered bushings and the highest torque rating per case size in the range. It comes in 12 case sizes up to 400 hp (300 kW), with torque ratings through 500,000 lb-in (56,500 Nm) and shaft sizes up to 7 inches (160 mm).

Typical users are conveyors, screw conveyors, agitators and aggregate, mining, cement, asphalt, grain and ethanol plants, the industries Dodge names for its sealing system. All reducers can be shaft-mounted, used as screw conveyor drives, mounted vertically or flange-mounted.

Technical specifications

Case sizes, nomenclature and accessories

The catalogue lists the sizes TA0107L, TA1107H, TA2115H, TA3203H, TA4207H, TA5215H, TA6307H, TA7315H, TA8407H, TA9415H, TA10507H and TA12608H. In a model code the TA prefix is the reducer, the next digit the case size, the three digits the AGMA reference and traditional bore, and a letter such as H marks the heavy-duty rating and extended bore. Ordering codes extend the base model, for example TA1107TB x 1-7/16 is the twin-tapered bushing kit for a 1-7/16 inch shaft, TA1107BG the belt guard, TA1107MM the motor mount, and TA1107SCA the screw conveyor adapter kit.

Accessories offered by Dodge are a tie rod kit, belt guard package, steel motor mount, lift-off sprag backstop that works with extreme-pressure lubricants, cooling fan, Hydra-Lock breather, bushing covers, an inboard shaft guard, CEMA adapters and three-hole driveshafts for screw conveyors, and an adjustable packing kit.

Selecting a Torque-Arm II

The catalogue easy selection covers electric motors up to 400 hp with output speeds up to 400 rpm. Class I is steady load and light shock for 10 hours a day, class II steady load over 10 hours or moderate shock, and class III moderate shock over 10 hours with heavy shock allowed for part of the day; peak starting loads should not exceed two, 2.8 and four times motor power respectively, otherwise the load is divided by that factor before the table is read. The reducer sheave must not be smaller than the minimum diameter in the selection table and should be mounted as close to the reducer as possible. Check the driven shaft and key for strength, and consult Dodge for extreme shock, non-motor drives or extreme temperatures.

Confirm before ordering: output speed and power, driven shaft diameter and length, mounting position, and which accessories are needed.

Features and construction

The Torque-Arm II is built around a sealing and mounting approach intended for continuous, dirty duty. Dodge lists a patented harsh-duty sealing system, twin-tapered bushings for installation and removal from the driven shaft, and the highest torque rating per case size in the range. The torque arm tie rod keeps the reducer from rotating while still allowing controlled movement as the driven shaft runs out, which reduces the loads placed on the internal bearings and gearing. The two-piece class 30 gray iron housing is doweled and precision machined, the helical gears are case carburised, and tapered roller bearings carry the shafts.

• Direct shaft mounting removes the coupling, base plate and foundation alignment work normally needed with a foot-mounted gearbox.
• Metal-reinforced oil seals with an external metal excluder lip are intended to keep abrasive dust and moisture out of the case.
• Shaft-mount, flange-mount and screw conveyor drive arrangements are available, plus vertical mounting.

Lubrication and maintenance notes

According to Dodge, the standard fluid is a petroleum-based rust and oxidation inhibited gear oil, ISO 220 or ISO 320, chosen by ambient temperature and output speed. A synthetic ISO 100 oil is suggested for low-temperature starts and a higher-viscosity synthetic for high ambient temperatures, which is relevant to units installed outdoors or near heat sources in the Gulf. Extreme-pressure oils are not needed for most applications but can be used where an external backstop is fitted and the oil is properly selected.

• Fill to the oil level plug that matches the mounting position; when output speed is below 15 rpm, fill to the highest plug.
• Change the oil every 2,500 hours or six months, whichever comes first, and shorten that interval in hot, wet or dusty surroundings. Synthetic oil and routine oil sampling can extend it.
• Use only catalogue-approved mounting positions, because some positions deliberately flood the input shaft area. For an inclined mounting or any arrangement not in the manual, confirm the oil level with Dodge application engineering.
• A backstop must be installed in an approved position and replaced as a complete assembly if it fails; it cannot be rebuilt in the field.

Installation checklist

Check the driven shaft diameter, keyway and shoulder against the bushing kit before lifting the reducer into place. Slide the unit onto the shaft, tighten the twin-tapered bushings in the sequence given in the manual, then fit the torque arm and tie rod so that the arm sits roughly at right angles to the line between the shaft and the anchor point. Mount the motor or sheave as close to the reducer as practical, keep belt guards fitted, and confirm the oil level only after the unit is in its final position. Rebuild kits, gearing reliability kits and remanufacturing services are offered by Dodge, and the reducer model number from the nameplate is needed to match them.

Typical applications

Torque-Arm II reducers are specified on belt and screw conveyors, mixers and agitators, bucket elevators and feeders where a shaft-mount drive saves space. Aggregate, mining, cement, asphalt, grain and ethanol plants are the industries Dodge associates with its sealing system, and similar dusty material-handling duty exists at quarries, ports and processing plants across the region.

Information needed for a quotation

• Full model or nameplate code, or the required output speed and power
• Driven shaft diameter, keyway and available length
• Motor power, speed and frame, and whether a belt drive or direct motor mount is wanted
• Mounting position and any accessories such as backstop, belt guard, motor mount, fan or screw conveyor adapter
• Ambient temperature range and dust or moisture exposure

Documents and quotation

The attached PDF is the Dodge Torque-Arm II flyer; ratings, nomenclature and selection steps come from the Dodge Torque-Arm catalogue, which is too large to host. Related gear units and motors are listed under Electric Motors and Gear Units. Send the application, power, speed and shaft size for a quotation.