5/8" to 3/4" Crankshaft Sleeve Adapter Pulley Bore Reducer

Crankshaft Sleeve Adapter – 5/8" to 3/4" Pulley Bore Reducer Bushing with Keystock

Upgrade your motor or pulley setup with this precision-made Crankshaft Sleeve Adapter. Engineered to adapt a crankshaft from a 5/8-inch diameter to a 3/4-inch diameter, this steel bushing sleeve allows you to fit pulleys with larger bores onto smaller shafts — no machining required. Includes a 3/16-inch keystock for secure, torque-resistant fitment.

Whether you're swapping pulleys for a different belt configuration, adjusting drive speed ratios, or repurposing motors with mismatched shaft diameters, this compact adapter delivers a reliable, tight fit every time.

Key Features

• Converts 5/8" shaft to 3/4" bore — instantly compatible with larger-bore pulleys and sheaves
• Includes 3/16" keystock — ensures positive, non-slip engagement between shaft and pulley
• Solid steel construction — durable, corrosion-resistant, and built for repeated use
• Fits standard sheave and pulley applications — ideal for motors, lawnmowers, compressors, and more
• No machining needed — drop-in fit for fast, straightforward installation

Specifications

• Inner Diameter (ID): 5/8 inch
• Outer Diameter (OD): 3/4 inch
• Keystock Size: 3/16 inch (included)
• Material: Steel

What This Adapter Does

This shaft sleeve bushing serves two primary functions:

1. Shaft Adaptation: Allows motors with a 5/8" shaft to accept pulleys or sheaves bored for a 3/4" shaft.
2. Drive Customization: Makes it easy to swap pulleys for different belt sizes or speed ratios without replacing the motor itself.

Ideal For

• Small engine and motor shaft upgrades
• Belt-driven equipment such as lawnmowers, compressors, and fans
• DIY mechanical and workshop projects
• Agricultural and industrial drive systems

For more information on safe tool and hardware use in mechanical applications, visit the OSHA Mechanical Safety Resources.

Frequently Asked Questions

Q: What does the 5/8" to 3/4" crankshaft sleeve adapter do?

A: This crankshaft sleeve adapter allows you to fit a pulley or sheave with a 3/4-inch bore onto a motor or engine shaft that measures 5/8 inch in diameter. It includes a 3/16-inch keystock to lock the pulley securely in place and prevent slipping during operation.

Q: What material is this pulley bore reducer bushing made from?

A: The bushing is constructed from solid steel, providing excellent strength and durability for both light-duty and demanding mechanical drive applications.

Q: Is keystock included with this shaft sleeve adapter?

A: Yes — a 3/16-inch keystock is included with the adapter, so you have everything you need for a secure, torque-resistant installation right out of the box.

Q: What types of equipment is this bushing compatible with?

A: This bore reducer bushing is compatible with any belt-driven equipment using standard sheave and pulley assemblies, including lawnmowers, air compressors, fans, small engines, and various workshop machinery where a 5/8" shaft and 3/4" bore combination is required.