GUARD 5A6897 - Caterpillar

Transmission Cooling (General Recommendations)Automatic transmissions generate heat due to converter slippage, charging pump losses, and friction in rotating components. The transmission fluid absorbs this heat and an oil cooler is required to dissipate the heat. Keeping the oil cool will maintain the lubricating properties of the oil, allow for the transmission to perform properly, and extend the life of the transmission components.The engine coolant (antifreeze) and the transmission fluid (TDTO) absorb the heat that is generated by the engine and the transmission. The two fluids carry the heat to a heat exchanger (radiator or cooler) so that the oil or antifreeze can be cooled.See the Transmission Application and Installation Guide, Engine Application and Installation Guide, and refer to Special Publication, SEBU6250, "Caterpillar Machine Fluid Recommendations" for specific transmission drive train oil and engine fluid requirements.____________________Converter CoolingCaterpillar Petroleum Transmissions have lockup clutches that reduce the heat that is generated by converters in all gears, except for first gear and for reverse. Under normal operating conditions, the transmission will upshift and downshift to the proper gear ratio and spend the majority of the operating time in the converter lockup clutch mode. The lockup clutch reduces the converter cooling requirements. If the driver selects first gear hold the lockup clutch is disabled. This mode of operation will result in continuous converter usage and the converter slippage will generate higher heat loads. The application, ambient temperatures, horsepower being transmitted, and the length of time in converter drive will dictate transmission cooling requirements.
Transmissions that are operated in converter drive for an extended period of time may over heat. In order to achieve optimum operating temperature, additional cooling capacity may be required to avoid damage to the transmission.
Temperature Operating LimitsThe maximum allowable transmission oil temperatures for normal (continuous) and intermittent conditions are the following:Continuous sump ... 90 °C (194 °F)Continuous converter out ... 99 °C (210 °F)Intermittent sump ... 99 °C (210 °F)Intermittent converter out ... 121 °C (250 °F)Oil Temperature GaugesIf the OEM chooses to use a transmission/converter color coded converter outlet temperature gauge, the following requirements and recommendations apply:Green - Safe zone is below 99 °C (210 °F)Yellow - Caution zone is 99 °C (210 °F) to 121 °C (250 °F)The following requirement applies:Red - Warning above 121 °C (250 °F)If the OEM chooses to use a transmission color coded sump temperature gauge, the following recommendations and requirements apply:Green - Safe below 90 °C (194 °F)Yellow - Caution between 90 °C (194 °F) and 99 °C (210 °F)The following requirement applies:Red - Warning zone above 99 °C (210 °F)
Operators may use the Yellow zone on an intermittent basis for short time intervals. Operation above the Red line for short periods of time can result in damage to the oil and the transmission.
Transmission OverheatingIn the unlikely event that the transmission does over heat, the transmission should be shifted to neutral and engine speed should be elevated to high idle until the transmission temperature returns to the proper operating temperature. Elevatin