The Midland Haldex Automatic Brake Adjuster (S-ABA) Kit, part number 40020304 or MD40020304, is a slack adjuster assembly designed for S-cam air drum brake systems on trucks and trailers. Key specs: 1-1/2" spline diameter with a 28-spline count, 5-1/2" arm length, 35° body angle, zero offset, and a 1/2" arm hole diameter. The anchor bracket style is plate and flat stud (bracket kit 42710563), and the straight grease fitting sits at the 180° position. Internal construction features high-alloy steel gears, a rolled wormshaft, heat-treated housing, and a centralized clutch. The clearance-sensing design maintains a constant, uniform gap between brake drum and lining, and the gradual adjustment cycle reduces the risk of over-adjustment during extended braking. Cross-references include OEM number 409-26010 and vendor codes HDX-40020304 and MD40020304. Call us to confirm proper fit for your axle and chamber configuration.
Features
1-1/2" spline diameter, 28-spline count
5-1/2" arm length, 35° body angle, zero offset
Plate & flat stud anchor bracket style; bracket kit 42710563 included
Straight grease fitting at 180° position
High-alloy steel gears with rolled wormshaft and heat-treated housing
Clearance-sensing design for consistent drum-to-lining gap maintenance
Tech Specs
- Spline Diameter: 1-1/2"
- Spline Count: 28
- Arm Length: 5-1/2"
- Body Angle: 35°
- Offset: 0
- Arm Hole Diameter: 1/2"
- Anchor Bracket Style: Plate & Flat Stud
- Bracket Kit: 42710563
- Grease Fitting Location: 180°
- Grease Fitting Type: Straight
- OEM Part Number: 409-26010
