Reduction hubs were fitted to splitscreen vans to reduce gear ratio so the original weedy 25hp engine could get a fully loaded van up hills !
The reduction hubs are at the ends of the axles behind the wheels, reduction ratios 1.39:1 pre-1964 and 1.26:1 1964-1967.
Since most splitscreen vans are running later more powerful engines (1500/1600tp) now, the reduction hubs are often considered a hindrance, so IRS conversion of splitscreen buses, which removes the reduction hubs is popular.
Reduction hubs can be rebuilt by replacing bearings/seals (parts available from SSVC club spares).
Servicing is limited to changing oil, 0.5 pint SAE 90 Hypoid oil per side, do not overfill.