🔩 Gear Coupling Flange – Leyland L/L (ZF), Height ~100 mm (Serrated)
📌 What It Is
A gear coupling flange for a ZF‑equipped Leyland L/L truck is a serrated (splined) flange that connects the output of the ZF gearbox to the propeller shaft companion flange/yoke in the driveline. It uses teeth/splines on its contact surface to provide positive mechanical engagement, ensuring efficient torque transfer from the gearbox to the driveshaft — especially important in heavy commercial vehicles like the Leyland L/L series.
Unlike a simple flange, a gear coupling is designed with a serrated torque surface that reduces slip and vibration under load, and its height (thickness) — in this case around 100 mm — influences the flange’s strength and engagement depth.
⚙️ Typical Specification (Aftermarket Catalog Reference)
From commercial vehicle parts catalog listings:
Attribute
Specification
Application
Leyland L/L with ZF gearbox
Part Type
Gear Coupling Flange (Serrated / Splined)
Spline / Teeth Count
~28 splines (common for Leyland ZF gear couplings)
Plate Diameter
~175 mm class (typical CV driveline plate)
Bolt Pattern
8 holes (common heavy truck pattern)
Bolt Size
~9.50 mm (15No class)
Height (Axial)
~100 mm (indicates deeper coupling engagement)
Surface Type
Serrated / Splined for torque engagement
In the parts list from aftermarket catalogs, a gear coupling flange specified as “L/L ZF HT.100MM” (serrated) is listed under standard gearbox coupling flanges for Leyland vehicles with ZF transmissions.
🛠️ Function in the Drivetrain
Here’s how it works within the vehicle:
✔ Connects Gearbox Output to Driveshaft: The flange bolts to the output shaft flange of the ZF gearbox and engages with the driveshaft’s companion flange, forming the torque path.
✔ Positive Engagement: Serrations or splines on the flange surface keep the connection tight and slip‑resistant under load — essential for a heavy truck’s high torque.
✔ Low Vibration & Backlash: Splined engagement helps dampen driveline vibration and reduces backlash compared with smooth flanges.
✔ Heavy‑Duty Design: The increased height (~100 mm) suggests a deep engagement surface, improving strength and durability for high‑load conditions.
🚚 Where It Fits
In a heavy truck like a Leyland L/L model with a ZF gearbox, the coupling flange sits right at the rear of the gearbox output:
Engine → Clutch → ZF Gearbox Output → Gear Coupling Flange (HT 100 mm) → Propeller Shaft → Differential → Axles → Wheels
It is one of the primary torque transfer interfaces between the gearbox and driveline.