Today I’d like to look at a component people often overlook; the “transfer case.”
Most off-highway equipment operates in a dirt road environment. Because of this, transmission power must be forwarded to both the rear and front axles. This is accomplished by the transfer case. This Tip will focus on the transfer case, what it does, how it does it, typical fluids, performance issues and support that we can provide to improve both equipment performance and customer productivity.
So grab a drink, sit back and let’s learn together.
Transfer Case Basics
The transfer case is a device that splits power between the front and rear axles. It is attached at the rear of the transmission and is most often of two or three shaft design. (See figure 1).
Transfer cases contain drive gears or chains, bearings, seals/gaskets, and drive shaft yokes. They may provide 1:1 gear ratio from the transmission or 2:1 if further transmission speed reduction is needed to improve vehicle traction. Most transfer cases have a clutch that allows decoupling from the front axle when conditions warrant.
Transfer cases are important as they distribute power to where it is needed. Though small compared to other components, a problem with a transfer case impacts the entire drive train and may disable the vehicle. Typical problems include:
Cost to repair or replace a heavy duty off-highway transfer case may be in excess of $2,000 for a rebuild kit (without gearing) plus labor. If you include 8 hours of downtime and lost productivity, the actual expense my exceed $120,000 in labor ($1,200 = 2 Men x $75 / Hr Labor Rate x 8 Hours) and lost productivity ($120,000 = 800 tons product impacted at $150/Ton). This number could be even higher if the repair parts are not on hand and cause further delays. These expenses can all be avoided through understanding how a transfer case operates and knowing the early warning signs of a problem before it becomes a major operational and productivity issue.
Mobil Transmission Fluids
Transmission fluids are used in most transfer case applications and are separate from the oils in the transmission. They provide engagement power and lubricate bearings, gears, chains, clutch packs and seals. In addition, transfer case lubricants (transmission lubricants) act as a heat transfer medium, and act as a lubricant for a control circuit if equipped. They must have an operating range from the lowest expected ambient temperature to over 150°C for extended periods. As such, transmission fluids for the transfer case must contain:
The recommendation for transmission oils is governed by the Original Equipment Manufacturers (OEM) for both on and off-highway equipment. Mobil products that are used in these applications include:
For additional products or product specifications, please refer to the current Mobil Product Data Booklet or consult your local Mobil representative. Also check out our additional content on our new Mobil Lubricants North America LinkedIn page. Until next time!