With their complex combination of mechanical, hydraulic, electrical, and computerized systems, automatic transmissions pose considerable challenges to seal designers. These inherent complexities in combination with increasing warranty demands, higher shaft speeds, and higher temperatures make the design of shaft seals for use as transmission seals no easy feat.

Generally speaking, there are two main types of transmission designs: rear wheel drive and front wheel drive. Rear drive designs typically employ an input seal (also known as the front seal) to prevent leakage of transmission fluid at the interface between the torque converter and the transmission case. Rear drive designs also use an output seal (otherwise known as the rear seal) to prevent leakage past the output shaft (where the transmission connects to the drive shaft).

In front wheel drive designs, an input seal prevents leakage between the torque converter and the transaxle. Front drive designs employ two output seals, one at both of the opposing interfaces between the transaxle and the front drive axles.

Figures 206 and 207 show two examples of input seal designs. Figure 206 shows a design incorporating a flange for easy removal. Figure 207 shows a dual lip designed to facilitate fluid separation. This design also features a flange to aid removal.

Figures 208 and 209 show two examples of output seal designs. Figure 208 shows a non-unitized design with shield and flange for easy removal. Figure 209 shows a unitized design featuring an axial dirt lip.

AUTOMOTIVE APPLICATIONS MAIN PAGE