Simplify with Automatic Transmissions

Automatic and automated transmissions have become very popular. They often increase productivity, reduce stress on the operators and protect the entire driveline from abuse caused by inexperienced drivers.

The Allison transmission has become a very popular option for vocational on/off-road use. These torque converter transmissions are capable of handling muddy and hilly jobsites, while increasing productivity by eliminating the power interruptions required when shifting a manual transmission. They also minimize costly clutch repair downtime that can be associated with a manual transmission. But there are steps you should take to maximize the investment in your automatic transmission.

Transmission fluid is the "life blood" of any automatic torque converter transmission. "In an automatic transmission, the fluid does considerably more than it does in a manual transmission," says Keith Duner, manager of service technology, Allison. "It is used to transmit power. It is used to actuate and release clutches. It is used to cool and lubricate bearings and friction material within the transmission. So it carries a heavy load."

These multiple demands require specialized fluids and regular maintenance to ensure trouble-free performance. "The selection as well as the maintenance of the fluid is critical to the life of the transmission," says Duner. "It is equal parts selection and long-term maintenance of the fluid."

Transmission fluids are designed to stay in the transmissions for relatively long periods of time. While there are many fluids approved for use in its automatic transmissions, such as DEXRON, fluids that meet the stringent Allison TES-295 specification offer several advantages. One such fluid is TranSynd, which was developed in cooperation with Castrol.

"For off-highway applications or rugged duty, we certainly recommend TES-295 fluid," says Duner. "Its oxidation rate is considerably less. Its ability to handle heat is considerably greater to the extent where, when used as we request, you can actually extend the fluid change interval of the transmission based solely on the fluid."

While TES-295 fluids will extend drain intervals, you still need to perform regular oil and filter changes, plus oil analysis to maximize life of the transmission. These service intervals are predicated on the duty cycle of the application and type of oil used as spelled out in the operator and mechanic manuals.

Oil analysis can also be used to determine drain intervals. You can monitor transmission health by using trend analysis, as well as ensuring the oil falls within safe limits as published in Technicians Guide for Automatic Transmission Fluid, part number GN2055EN. This document is available for purchase via the Allison Internet site (www.allisontransmission.com).

Keep it cool

The amount of heat generated really depends on the application. Off-road applications tend to generate more heat. "An on/off- road vehicle equipped with one of our transmissions has a different calibration than one that is a pure on-highway duty cycle," says Duner. "As a result, we control the amount of time that we spend in lock-up clutch vs. converter mode separately.

"Converter mode is great for traction, but it is a heat generator," he continues. "So we monitor that and apply it differently in an off-highway application."

To keep everything operating as designed, you need to properly maintain the cooling system, which is typically shared with the engine. This is particularly important with trucks that run off road.

"You are in a high dust, high dirt environment, which raises the likelihood of the coolant system being plugged and clogged with foreign debris and material," says Duner. "So getting in there with your radiator comb and making sure that your fins are clear and accessible is a reasonable thing."

Watch for coolant leaks