Service Tips

  1. What maintenance procedures should on-/off-highway truck operators follow to ensure a transmission does not fail prematurely? Is it a combination of operating techniques and simple maintenance procedures, or other criteria?
  2. What components in a transmission system are the most sensitive to contamination?
  3. What are the primary causes of transmission failure for trucks used in the construction/demolition sector? How could failures be avoided?
  4. What lube should I use for Eaton axles and Fuller transmissions?
  5. When should I adjust my clutch?

 

Q: What maintenance procedures should on-/off-highway truck operators follow to ensure a transmission does not fail prematurely? Is it a combination of operating techniques and simple maintenance procedures, or other criteria?

  1. Optimum performance and reliability of heavy-duty automatic transmissions can be noticeably influenced by the type of fluid used and the frequency with which that fluid is changed. Allison Transmission Division and General Motors have designed extensive programs including specifications and tests to verify the quality of fluids and consequently have specific fluid and filter change recommendations. These fluid and internal filter change interval recommendations are listed in the respective transmission series operator’s manuals. Additionally, because the transmission fluid cools, lubricates, and transmits hydraulic power, it is important that the proper fluid level be maintained at all times. If the fluid level is too low, the converter, bushings, bearings, and clutches do not receive an adequate supply of fluid. If the fluid is too high, the fluid can aerate. Aerated fluid can cause the transmission to shift erratically or overheat. Additional information regarding fluid/filter change recommendations and maintaining proper fluid level are contained in the MD/HD/B Series Allison On-Highway Transmissions (WTEC III Controls) Operator’s Manual – OM2995EN.

Q: What components in a transmission system are the most sensitive to contamination?

  1. Solid particulate contamination may have a detrimental effect on the durability of bushings and roller bearing elements inside the transmission. Additionally, fine particulates may degrade the functionality of components in the control module by causing solenoid valves to fail or clutch apply valves to stick.
    The presence of water and/or ethylene glycol coolant mixtures in the transmission oil is detrimental to the reliability and durability of the internal components. This foreign liquid has a deteriorating effect on non-metallic components (rubber, gasket material, etc.) and on highly loaded steel parts, such as bearings and gears, due to reduced lubricity. Frictional capacity of drive clutch plates can be greatly reduced, as a result of surface film or impregnation and the presence of glycol will physically deteriorate clutch plate material.

Q: What are the primary causes of transmission failure for trucks used in the construction/demolition sector? How could failures be avoided?

  1. The single most significant method for ensuring years of trouble-free service is to perform the recommended transmission fluid and filter maintenance. Some fleet owners have successfully implemented oil analysis programs to monitor and control fluid change intervals as well as provide a means of early detection of pending problems. Additionally, periodic inspections of those truck systems that might directly influence transmission operation such as the vehicle’s drive shaft components, electrical charging system, and the transmission oil cooler/vehicle cooling system, etc. should be performed to ensure that deficiencies in these systems do not lead to a transmission malfunction.

Q: What lube should I use for Eaton axles and Fuller transmissions?

  1. Roadranger lubrication policy allows the use of general service lubricants that meet mil specs 2104D for transmission and 2105E for axles, and these lubricants require changes of 60,000 and 120,000 respectively. With the use of synthetics change intervals are extended to 250,000 miles.

Q: When should I adjust my clutch?

  1. The time to adjust is before a loss of “free pedal”. Do not wait until the clutch starts slipping. Allowing the clutch to slip will result in reduced life or complete failure. Consult O.E. Service manuals or Eaton clutch for proper set-up instructions. If your truck is equipped with a Fuller Solo clutch, “Free Pedal” will be maintained and no adjustments will be necessary.