What is Bendix Drive? Construction and Operation.

Types Of Drive Arrangements

The drive arrangements may be of the two general types. It includes Bendix and Folo-Thru drive.

1. Inertia drive:

  • Bendix drive
  • Folo-Thru drive

2. Overrunning clutch drive.

Bendix Drive

The Bendix drive is the most common type of drive arrangement used in the vehicles. It is simpler in construction and works on the inertia principle. Nowadays advanced types of self-starters are available in the market but for a basic understanding of self-starters, you need to analyze this arrangement first.


The Figure shows the Bendix drive for starting the motor. It is fastened in the armature shaft of the starting motor. The drive head is keyed to the end of the armature shaft. The pinion gear, which has internal threads, is mounted on a threaded sleeve, just like a nut on a bolt. The sleeve is not connected directly to the shaft of the starting motor but uses it only as a bearing. A spring is attached on the drive head and also to the sleeve.

Bendix drive
Live picture of Bendix

Watch the Bendix drive pinion arrangement below:

Bendix drive pinion arrangement


When the starting motor is at rest the pinion gear is not engaged with the flywheel. When the starting motor is switched on, the armature starts to rotate. This causes the threaded sleeve to rotate also because the sleeve is fastened to the armature shaft through a spring. The pinion, because of its inertia of rest and its unbalanced weight, turns very little, but it moves forward on the revolving volt until it engages with the teeth of the flywheel.

The slight turning of the pinion gear helps to engage it properly with the flywheel. When the pinion gear strikes with the collar, it begins to turn with the sleeve, causing the flywheel to run with it. When the flywheel turns, the crankshaft also turns and the engine starts. The spring between the armature shaft and the threaded sleeve takes the shock of the start.

Bendix drive
Bendix drive

After the engine has started, the pinion gear is turned by the engine much faster than when rotated by the starting motor. This causes the pinion gear to turn back on the threaded sleeve, making it disengaged with the flywheel.

Watch the Bendix drive live engagement below:

live engagement

Also, Read These Posts

  1. What is Folo-Thru drive? Construction and Operation.
  2. Car Starter or Starter Motor Problems.
  3. What is Over-Running Clutch Drive? Applications Of Over-Running Clutch.
  4. What is Starter Motor? Construction and Operation of Starter Motor.


Creative Blogger And Automobile Engineer.

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