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Operating Temperatures

  • With Eaton® Roadranger® CD50 Transmission Fluid Heavy Duty Engine Oil and Mineral Oil

The transmission should not be operated con- sistently at temperatures above 250°F (120°C). However, intermittent operating temperatures to 300°F (149°C) will not harm the transmis- sion. Operating temperatures above 250°F increase the lubricant’s rate of oxidation and shorten its effective life. When the average operating temperature is above 250°F, the transmission may require more frequent oil changes or external cooling.

The following conditions in any combina- tion can cause operating temperatures of over 250°F: (1) operating consistently at slow speeds, (2) high ambient temperatures, (3) re- stricted air flow around transmission, (4) ex- haust system too close to transmission, (5) high horsepower, overdrive operation.

External oil coolers are available to reduce operating temperatures when the above condi- tions are encountered.

Transmission Oil Coolers are: Recommended

  • With engines of 350 H.P. and above

with overdrive transmissions Required

  • With engines 399 H.P. and above with overdrive transmissions and GCW’S over 90,000 lbs.

  • With engines 399 H.P. and above and 1400 Lbs.-Ft. or greater torque

  • With engines 450 H.P. and above

  • With EP or Multipurpose Gear Oil

Mild EP gear oil and multipurpose gear oil are not recommended when lubricant operating temperatures are above 230°F (110°C). In addi- tion, transmission oil coolers are not recom- mended with these gear oils since the oil cooler materials may be attacked by these gear oils. The lower temperature limit and oil cooler restriction with these gear oils gener- ally limit their success to milder applications.

Proper Lubrication Levels as Related to Transmission Installation Angles

If the transmission operating angle is more than 12 degrees, improper lubrication can oc- cur. The operating angle is the transmission mounting angle in the chassis plus the per- cent of upgrade (expressed in degrees).

The chart below illustrates the safe percent of upgrade on which the transmission can be used with various chassis mounting angles. For example: if you have a 4 degree transmis- sion mounting angle, then 8 degrees (or 14 percent of grade) is equal to the limit of 12 degrees. If you have a O degree mounting angle, the transmission can be operated on a 12 degree (21 percent) grade.

Anytime the transmission operating angle of 12 degrees is exceeded for an extended period of time the transmission should be equipped with an oil pump or cooler kit to insure proper lubrication.

Note on the chart the effect low oil levels can have on safe operating angles. Allowing the oil level to fall 1/2" below the filler plug hole reduces the degree of grade by approxi- mately 3 degrees (5.5 percent).

Proper Lubrication Levels are Essential!

Transmission Mounting Angle

Dotted line showing “2 Quarts Low” is for reference only. Not recommended.

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