Replacement Variable Speed Pulley for
Wheel Horse RJ25 & RJ35 Garden Tractors (1955-1957)
This variable speed pulley set is made to be a direct replacement for the original found on Wheel Horse garden tractors (with reverse) made from 1955 through 1957. The Wheel Horse part number is 1851. An installation tip sheet is included.
Variable speed occurs because when properly installed the center section slides from side to side to change the effective pitch of both pulley grooves at the same time. The v-groove on the outside of the large diameter section is for the reversing disk to ride in. 
The hollow center shaft is made of steel and the 3 pulley sheave sides are made of cast iron just like the originals. The roller bearings are the same as the originals, that part number is still available. The outer pulley sheaves are pressed onto the hollow center shaft, and a set screw is added at each joint to assure they never move, the same way the originals were made. The center pulley sheave is keyed to the hollow center shaft with a woodruff key. This ensures the center sheave rotates together with the outer sheaves and can slide smoothly from one side to the other. The hollow center shaft is drilled to allow grease to pass to the movable pulley sheave just like the originals. The zerk for greasing is located on the end of the shaft that this pulley set rides on.
The 3 pulley sheaves and hollow center shaft are custom machined. Dimensions for the machined parts were acquired by disassembling and measuring multiple original pulley sets. 
Grease was applied under the movable pulley sheave during assembly, no other grease was added. Grease should be applied to the bearings during assembly, and added through the grease zerk as required. Wipe any grease from the bottom of the pulley grooves to prevent it from getting on the belts during operation.
This pulley set is not painted so you can paint or weather it to fit the application. When painting the pulley set, move the center sheave towards the larger fixed sheave with the v-groove in it. This allows the movable sheave to cover the hollow center shaft. Don’t allow any paint to get on the hollow center shaft because it will prevent the movable sheave from sliding properly.
View all of the pictures for details. The last few pictures show a pulley set after it was painted and installed on a tractor. The belt guard has been removed for pictures. The belt guard must be in place and adjusted properly or the belt will not release for neutral when in operation.