What is a propeller shaft?
A propeller shaft (also called a drive shaft or cardan shaft) is a rotating shaft that transmits torque from the gearbox (or transfer case) to the differential in a rear-wheel-drive (RWD), four-wheel-drive (4WD), or all-wheel-drive (AWD) vehicle.
Because the gearbox and differential are often far apart, the propeller shaft must be long, lightweight, and capable of withstanding torsional and bending stresses — which is why it is made as a tubular shaft.
Number of Tubular Shafts in a Propeller Shaft Assembly
The number of tubular sections (or shafts) in a propeller shaft depends on the length of the vehicle and the drivetrain layout.
Let’s look at the common configurations:
| Vehicle Type | Typical Layout | Number of Tubular Shafts | Description |
|---|---|---|---|
| Short wheelbase vehicles (cars, small vans) | Gearbox and differential close together | Single tubular shaft | One long hollow tube connects gearbox to differential directly. |
| Medium wheelbase vehicles (pickup trucks, larger vans) | Slightly longer distance | Two tubular shafts | A front and a rear shaft connected by a center bearing (support bearing) and universal joints. |
| Long wheelbase or heavy-duty vehicles (buses, trucks, 4WD vehicles) | Very long distance between gearbox and rear axle | Three or more tubular shafts | Multiple sections connected by universal joints and supported by intermediate bearings to prevent vibration and bending. |
🧩 Typical Multi-piece Propeller Shaft Arrangement
For example, in a two-piece propeller shaft:
- Front tubular shaft — connected to the gearbox output via a slip joint and universal joint.
- Rear tubular shaft — connected to the center bearing and rear differential via another universal joint.
- Center bearing (support bearing) — supports the joint between the two shafts to reduce vibration and bending stress.
In a three-piece propeller shaft, there would be:
- Front, intermediate, and rear tubular shafts,
each connected by universal joints and supported by two center bearings.
🧱 Why Tubular?
- Lightweight: Hollow tubes reduce mass and inertia.
- Strong: Circular cross-section resists torsional stress.
- Efficient: Easier to balance dynamically.
- Flexible: Can be easily joined with universal joints.
🧮 Summary Answer
| Vehicle / Application | Typical Number of Tubular Shafts |
|---|---|
| Passenger car (RWD) | 1 |
| Light commercial vehicle | 2 |
| Heavy truck / Bus | 2 or 3 |
| Very long chassis (multi-axle truck) | 3 or more |
✅ In summary:
A propeller shaft typically consists of 1 to 3 tubular shafts, depending on the distance between the transmission and the differential:
- 1 for short drives,
- 2 for medium wheelbase vehicles,
- 3 or more for long or multi-axle vehicles.
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