Weichai Timing Gear Housing | Diesel Engine Gear Case

Rust prevention treatment on internal machined surfaces; external surfaces can be painted or kept in original finish.

The timing gear housing is a cast iron cover bolted to the front of the engine block. It encloses the timing gear train — crankshaft gear, camshaft gear, injection pump drive gear, and air compressor drive gear. Three jobs it has to do well:

1. Keep dust, water, and dirt away from the gear teeth.
2. 充当齿轮啮合的”骨架”，保证各齿轮中心距和啮合关系稳定
3. Seal the oil inside. A bad seal means oil leaks and gears run dry.

正时齿轮室出问题，常见表现有三种：机油渗漏、齿轮异响、发动机抖动。一旦壳体变形或者密封面不平，直接影响正时精度，重则顶气门。所以这是一件”看着不起眼、坏了很要命”的零件。

二、Material and process

A timing gear housing is not a complex shape. But the material and machining matter more than the shape does. Here is how we run it:

1. Mold. All 10 part numbers run on metal molds. Wood is only for samples.
2. Mold. All 10 part numbers run on metal molds. Wood is only for samples.
3. Casting simulation. Before we pour, we run MAGMA software on the fill pressure and temperature field. This catches shrinkage cavities before they happen in the metal.
4. Heat treatment. HT250 gets stress-relief annealing. QT500-7 gets annealing plus quench and temper.
5. Machining. Vertical machining centers, plus our in-house 5-axis units.
6. Inspection. Every critical bore and face runs through a CMM. Flatness, symmetry, position — all logged.
7. Mock-up test. The housing is bolted to a fixture to check sealing face flatness before packing.

Material choice by application：

• Highway trucks (HOWO 7, Steyr) — HT250 is enough. Lower cost, good rigidity.
• Mining and dump trucks (HOWO 6×6, Auman mining spec) — QT500-7 recommended.
• High altitude, heavy load, long grade (think Tibet, Xinjiang long-haul) — QT500-7 with thicker wall.

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三、How to avoid the wrong part

A wrong housing costs you a gear set, sometimes an engine. Three checks before you order:

1. 认 OE 号：直接用规格编号下单，比如 61260001194B，不要用”WD615 齿轮室”这种模糊描述
2. Read the stamp on receipt. Every housing we ship has the part number stamped on the side. Check it before you sign the B/L.
3. Measure the critical dimension. On WP10, the distance from the dowel pin bore to the center bore differs between Euro III and Euro IV. Measure before installation.

If you are not sure, send a photo of the old part (with the stamp visible). We usually confirm the part number within 1–2 hours.