🔩 Pinion Coupling / Differential Coupling Flange – Leyland L/L 350 & L/L 370 Tusker
📌 Component Overview
The pinion coupling flange (also called differential coupling flange) is a drivetrain interface part mounted on the rear axle pinion shaft output. It connects the differential’s pinion gear output to the propeller shaft or carrier flange, allowing torque from the rear differential to be transmitted smoothly into the driveline. This flange typically has serrations (splined teeth) on its contact face to ensure positive mechanical engagement with the mating partner, reducing backlash and slippage under heavy load.
⚙️ Key Specifications (Leyland L/L 350 / 370 Tusker)
According to Leyland spare parts catalogs:
Application: Leyland L/L 350 and L/L 370 (Tusker) trucks (rear differential output flange).
Flange Type: Serrated / splined pinion (differential) coupling flange.
Splines: ~10 splines/teeth on the coupling surface.
Bolt Holes: 4 bolt holes for mounting the flange to the differential output shaft yoke or companion flange.
Plate Diameter: ~146 mm (6 inch class coupling plate).
Height / Thickness: ~85 mm (typical overall flange height thickness measured from the mating face).
OEM Part References: Common Leyland catalog numbers for this flange include F1432611 / F1430922 or equivalent flank codes in parts lists.
👉 This part is listed under “DIFFERENTIAL/PINION COUPLING FLANGE” in standard Leyland spare parts catalogs for L/L 350/370 (Tusker). It’s meant to match the pinion output to the driveshaft or next driveline segment reliably.
🛠️ Function & Importance
The pinion coupling flange plays a critical role in the final‑drive assembly:
✔ Torque Transmission: Transfers torque from the differential pinion shaft to the propeller shaft or companion yoke downstream.
✔ Positive Engagement: Serrated / splined surface improves mechanical lock and reduces backlash under high torque conditions.
✔ Drivetrain Alignment: Maintains correct geometry between the rear axle differential and the propeller shaft, reducing vibration and wear on universal joints.
Without this flange, the rear axle could not reliably send power to the driveline, leading to drivability issues or drivetrain failure.
📌 Where It Is Installed
The pinion coupling flange is bolted directly onto the rear axle’s pinion output (inside or at the rear of the differential housing).
From there, it engages with the propeller shaft companion flange or yoke, completing the torque path all the way to the wheels.
🧰 Common Checks on Servicing
When replacing or servicing this flange:
Inspect the splines/serrations on both the pinion flange and mating part for wear or rounding.
Check the bolts and torque specs — these need to be tightened to manufacturer‑specified torque to avoid loosening under load.
If present, ensure the oil seal (if integrated) is replaced to prevent rear differential oil leakage.