Tuff Torq K46 Transmission Drive Pulley 1A646025840 — 4.90" Diameter, 1/2" Spline OEM Replacement

Tuff Torq Genuine 1A646025840 is a direct-fit K46 hydrostatic transmission splined drive pulley — 4.90" diameter with a 1/2" spline — engineered to replace worn or damaged pulleys on compatible John Deere units.

This OEM drive pulley is manufactured by Tuff Torq to the original equipment specifications for the K46 series hydrostatic transmissions. It restores proper belt engagement and torque transfer for tractors and mowers that use the K46 or related K57/K57Z families. The part number 1A646025840 ensures compatibility when ordering and helps avoid returns from incorrect fitment.

Will this pulley fit my John Deere model?

Check the serial or model ranges of your machine against the listed compatible transmissions. Tuff Torq supplies this pulley for many K46BR and K46CC serial blocks as well as K57AR and K57Z ranges; matching the transmission code and serial range is the fastest way to confirm fit.

• Compatible with K46BR serial ranges 0015115–0145601 and onward as listed.
• Fits multiple K46CC ranges including MY18 AJZ series entries.
• Also compatible with K57AR and K57Z designations in the listed ranges.
• Use part number 1A646025840 when ordering to avoid fitment errors.

How does this pulley affect performance and belt life?

A correctly sized and machined pulley maintains proper belt alignment and tension, which reduces slippage and uneven wear. Replacing a worn pulley can restore efficient power transfer from the hydrostatic transmission to cutting decks or implements, reducing belt stretching and premature failure.

• 4.90" diameter and 1/2" spline match original specifications for intended machines.
• OEM machining tolerances ensure concentric rotation and smooth belt tracking.
• Proper fit reduces vibration and slippage that shorten belt life.
• Using a genuine Tuff Torq part retains original drivetrain geometry.

What should I inspect before installing the pulley?

Before installation, verify the shaft splines, keyway (if applicable), and surrounding hardware are in serviceable condition. Clean mating surfaces, inspect bearings and seals nearby, and confirm belt condition; replacing the pulley while other components are compromised may lead to repeat repairs.

• Inspect transmission output shaft splines for wear or deformation.
• Check the belt for glazing, fraying, or uneven wear and replace if needed.
• Examine adjacent bearings and seals for leaks or play.
• Follow torque specs for fasteners and confirm secure seating before operation.

Is this an OEM part and how do I order the correct item?

This is a genuine OEM Tuff Torq pulley bearing part number 1A646025840, not an aftermarket copy. Ordering by the exact part number and confirming your machine’s transmission code (K46BR, K46CC, K57AR, K57Z) and serial range will ensure you receive the correct pulley for a direct replacement.

• Part number: 1A646025840 — use it when searching or ordering.
• Listed as a Tuff Torq genuine K46 hydrostatic transmission component.
• Direct-fit sizes: 4.90" diameter with a 1/2" spline to match originals.
• Contact dealer with your transmission code and serial number for verification.

Who this is for: This pulley is intended for owners, service technicians, and dealers who maintain John Deere lawn and compact utility tractors that use Tuff Torq K46 or compatible K57 hydrostatic transmissions. It's ideal for anyone restoring correct drivetrain function after pulley wear, replacing damaged parts after belt failure, or keeping a parts inventory for routine service. If you need a direct OEM replacement that preserves factory fit and belt geometry, this Tuff Torq 1A646025840 pulley is made for that purpose.