Bendix starter - what is it? Photo
It is difficult for a person unfamiliar with automotive terms to understand what certain names mean. A distributor, a jet, a bendix, a rocker, a trunnion and so on - you must admit, not many will understand what is at stake. In addition, abbreviations can often be seen in the literature: SHRUS, PTF, KSHKh, ZDT, cylinder head. However, knowing the meaning of all these terms is necessary at least in order to buy the right part in an auto parts store.
If you have problems with the starter, then one of the reasons may be a breakdown of the bendix. The picture is familiar: you are trying to start the engine, you can hear the retractor relay clicking, and then a characteristic rattle - the overrunning clutch gear does not engage with the crankshaft flywheel crown. So it's time to check the condition of the bendix and its gears.
In the parts catalog, this part is usually referred to as the starter drive or overrunning clutch. In the common people, this clutch is also called a bendix, in honor of the American inventor who patented it. The bendix plays a very important role - it is through it that the rotation of the starter armature shaft is transmitted to the crankshaft thanks to the driven cage with the gear.
We have already written on our website Vodi.su about the situation when the starter is spinning, but the car will not start.
We also recall the principle of operation of the starter:
- current from the battery is supplied to the starter motor winding;
- the armature shaft begins to rotate, on which the overrunning clutch is located;
- there are splines on the shaft, along them the bendix moves to the flywheel;
- the teeth of the bendix gear mesh with the teeth of the flywheel crown;
- as soon as the flywheel spins up to a certain speed, the starter drive gear is disconnected and the bendix returns back.
That is, as we can see, there are two key points: the transfer of rotation from the armature shaft to the starter flywheel, and the disconnection of the bendix gear when the flywheel reaches a certain number of revolutions per minute. If disconnection does not occur, then the starter will simply burn out, because the maximum rotation speed of the armature shaft is much lower than the rotation speed of the crankshaft.
It is also worth noting that the starter drive gear can only rotate in one direction.
Starter bendix device
The main elements of the drive are:
- driven cage with gear - provides engagement with the flywheel;
- leading clip - located on the starter armature shaft and rotates with it;
- buffer spring - softens the moment of contact of the gear with the flywheel crown (sometimes the clutch does not occur the first time and thanks to this spring the gear bounces back and re-engages);
- rollers and pressure springs - allow the gear to rotate in only one direction (if the rollers are erased, the gear will slip when the engine starts).
Most often, breakdowns occur due to wear of the teeth of the starter drive gear. In this case, you have to remove the starter and replace the bendix, although in some stores you can find repair kits in which the gear is sold separately. Be that as it may, it is quite difficult to repair a starter without proper preparation.
Less commonly, the buffer spring is weakened. It is also easy to make sure that it is loosened - when you turn the key in the ignition, you can hear a rattle. The engine will start, but such misalignment of the teeth will lead to rapid wear of both the bendix gear and the flywheel ring (and its repair will cost much more than replacing the bendix).
Also, the cause of the breakdown can be a break in the bendix plug, which connects the bendix to the retractor relay. If this fork breaks, the freewheel gear will not engage the flywheel.
Over time, the rollers that are in the leading clip can also be erased. They look very small, but it is thanks to them that the gear can rotate in only one direction. If the gear rotates freely in all directions, then this indicates either marriage or complete wear of the rollers and weakening of the pressure plates.
It is worth saying that the starter is a rather complicated device and breakdowns most often do not occur due to the bendix. The life of the starter is much less than that of the engine, so sooner or later it will still have to be replaced.
Video about how the bendix was restored when repairing the starter.
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