Which planetary gear control element is commonly adjustable from outside the transmission housing?

Which planetary gear control element is commonly adjustable from outside the transmission housing?

• A. Hydraulic clutch
• B. Sprag-type one-way clutch
• C. Servo and band mechanism
• D. Roller-type one-way clutch

Answer: (C)

In planetary gear transmissions, the element that actually locks or cancels a gear is the band wrapped around a drum, operated by a hydraulic servo. That band needs the right amount of clearance and pre-load to engage smoothly and hold tension without slipping. Technicians can adjust this by an external screw or adjuster on the outside of the transmission housing, making it possible to set the band clearance without taking the case apart. The other options—hydraulic clutches, sprag-type, and roller-type one-way clutches—are internal and controlled by hydraulic pressure or their internal geometry, not designed for external adjustment during routine service. So the servo and band mechanism is the one commonly adjustable from outside the housing.