📌 Thru Shaft – Leyland/L/L 3118, 3123 & Eicher 40.40 (Heavy-Vehicle Drivetrain Component)
🚛 What Is a Thru Shaft (Through Shaft)?
A thru shaft (also called through shaft) is a mechanical power-transmitting shaft used in the drivetrain or axle assemblies of heavy commercial vehicles. It is designed to transmit torque and rotational motion directly between joined components (such as between gearbox, differential, or axle parts) while allowing the structural housing or surrounding assembly to pass over it. It differs from a simple propeller shaft by being more integrated into the gearbox/axle output or input assembly, not just a separate rotating tube.
In truck drivetrains, shafts like these can be used to:
link transmission output to the propeller shaft yoke,
connect propeller shaft to differential,
or act as an internal spline / sliding shaft that maintains torque transmission while allowing axial movement.