How to Distinguish Fast and Slow Gearboxes in FAST?
2 Answers
The gearbox with an 'A' after the serial number is a fast one, while those without the 'A' are slow gearboxes. Rotate the front intermediate shaft and mark it. If the front rotates one turn and the rear output coupling plate also rotates one turn, it indicates a slow gearbox.
I often work on repairing transmissions for trucks. Fast and slow transmissions from FAST Gear are mainly distinguished by gear ratios and model numbers. Fast transmissions have smaller gear ratios, making it easier to reach higher speeds and save fuel, which is ideal for long-distance highway driving. Slow transmissions have larger gear ratios, providing more torque and better performance for climbing hills and hauling heavy loads. Specific models like the RT11509C have an 'H' indicating a high-speed type, while 'R' stands for low-speed. Once, a truck owner realized something was wrong only after changing the transmission—the speed wouldn't pick up after shifting gears. Checking the nameplate or user manual makes it clear. Pay attention to the difference in shifting feel while driving—low-speed transmissions have tighter gear engagement in low-speed ranges, providing stable acceleration but limiting top speed. If unsure, consult a professional repair shop to avoid damaging the vehicle or delaying work. Remember to verify information during regular maintenance to prevent confusion.
