Dodge SD QD Bushing, Keyed, Three-Bolt Flanged, Ductile Iron

Genuine Dodge SD series QD bushings in ductile iron, supplied with keyseat. The SD sits one size below the SK in the QD range: a three-bolt flanged bushing rated 5,000 lb-in, with a 4 degree tapered bore that draws down onto the shaft as the three cap screws are tightened. It mounts and dismounts without a puller and holds the sheave concentric under load.

Three stock bores are listed here: 1-3/8 in. (Dodge 120378), 1-5/8 in. (Dodge 120382) and 1-7/8 in. (Dodge 120386). Pick the bore that matches your shaft.

Key specifications

• Series: Dodge SD, QD standard
• Torque rating: 5,000 lb-in
• Hardware: three 1/4-20 x 1-7/8 in. cap screws, supplied with the bushing
• Installation torque: 108 lb-in. Do not exceed it. Over-torquing a QD bushing cracks the sheave hub
• Flange outside diameter: 3.18 in.  |  Flange thickness: 0.43 in.  |  Bolt circle: 2.69 in.
• Barrel diameter: 2.18 in.  |  Length through bore: 1.81 in.
• Minimum hub diameter: 3.81 in. in class 30 cast iron, 3.50 in. in steel
• Bore range for the series: 1/2 in. minimum. In ductile iron, 1-11/16 in. maximum with a full keyway, 1-15/16 in. with a shallow keyway, 2 in. unkeyed
• Taper: 4 degrees. Mounts conventionally or reversed
• Material: ductile iron

Bore, keyway and weight by size

• 1-3/8 in. bore (120378): keyseat 5/16 x 5/32 in., 5/16 in. square key. 1.50 lb
• 1-5/8 in. bore (120382): keyseat 3/8 x 3/16 in., 3/8 in. square key. 1.29 lb
• 1-7/8 in. bore (120386): shallow keyseat 1/2 x 1/16 in., shaft keyseat 1/2 x 1/4 in., 1/2 x 5/16 in. key furnished with this size. 1.07 lb

The 1-7/8 in. bore is past the SD series limit for a full keyway, so Dodge supplies it with a shallow keyseat and furnishes the matching key. That is correct for the part, not a catalog error, but it does mean the key is not standard square stock. Keep it with the bushing.

Fitment

SD bushings fit any sheave, sprocket, timing pulley or coupling hub bored for the SD QD size. They are not interchangeable with the larger SK bushing, nor with the two-screw Type H bushing used in bushed fractional-horsepower sheaves. Check what your hub is bored for before ordering. SD is called SD by every major maker, so there is no cross-brand letter to translate.

Installation

Wipe the taper and the hub bore clean and dry. Do not use anti-seize, oil or any lubricant on the mating taper surfaces, which makes the bushing over-advance and crack the hub. Line up the keyways, start all three cap screws, then tighten them in rotation to 108 lb-in. Recheck after a few hours of running, and again after the first belt re-tension.

QD is a registered trademark of Emerson Electric. Not sure which bushing your sheave takes? Send us the sheave part number or a photo of the hub and the Warthog Air Compressor Store team will confirm before you order.