SLACK ADJ 10 SPL

🔧 Slack Adjuster – 10 Spline Overview

⚙️ What It Is

A 10‑spline slack adjuster is used in heavy-duty air-brake systems on trucks and trailers. It fits over a 1.25″ (1 ¼”) camshaft and translates brake chamber force into mechanical adjustment of brake shoes or linings—with either manual or automatic reset.

🧱 Common Specifications

• Spline Diameter: 1.25 inches (1 ⅛” is less common; always measure to be sure)

• Spline Count: 10 teeth (standard specification for 10-spline type adjusters)

• Arm Span (Lever Length): Usually 4.5″ to 5.5″ or 5.5″ to 6.5″ center-to-center between clevis and camshaft – depending on variant

• Clevis Hole: ½″ diameter hole for attaching to brake rod linkage (standard)

• Offset/Arm Type: Available in straight or offset styles (e.g., 5/8″ offset exists)

• Adjustment Type:

  • Manual Slack Adjuster: Requires manual rotation to take up slack

  • Automatic Slack Adjuster: Automatically compensates brake shoe wear during operation

🔄 Typical Variants

🛠 Manual 10‑Spline Adjuster (Straight Arm)

• 1.25″ camshaft × 10 spline

• Arm length: Typically 5.5″ (some offer adjustable spans like 5.5″ to 6.5″)

• Straight design, bronze bushings, standard-duty rating per SAE J1461

• Examples: Pro-Trucking Products 278326, Velvac standard adjuster

⚙ Automatic 10‑Spline Adjuster

• Same spline/camshaft profile (1.25″ × 10)

• Arm spans commonly 5.5″ or 6.0″

• Corrosion-resistant coatings, clearance/load sensing auto-adjust design

• Notable part numbers: Haldex 40010155M1D, Meritor R801041/R801042, Sirco CB21102/CB21103

🧩 Dimensions & Usage Table

✅ Final Takeaway

A 10‑spline slack adjuster reliably connects the brake chamber piston to the camshaft in heavy-duty brake systems. When designed for 1.25″ camshafts, it is available in manual or automatic variants, with arm spans ranging from ~4.5″ to 6.5″, straight or offset types, and a standard ½″ clevis hole. Automatic versions (e.g., Haldex, Meritor, Sirco) provide self-adjusting convenience, while manual types (e.g., PTP, Pro-truck) are simple, serviceable, and often more economical.