The main benefit of gear reduction is that it allows for significantly smaller starters that produce an equal or greater amount of torque in comparison to much larger direct drive starters. The main drawback is that they are typically more expensive.

When replacing a direct drive starter with a gear reduction model, there is more space around it, which makes installation easier and may improve heat-resistance of the solenoid. However, “soft-start” gear reduction starters may require the additional cost of a magnetic switch installed in the solenoid circuit.

In a DD starter, components are attached in a line and run off the armature. A PMGR starter is similar to a PLGR starter except the PMGR starter uses permanent magnets instead of field coils. Similarly, PMDD starters are akin to DD starters except PMDDs use permanent magnets instead of field coils.

The two main types of starters are Manual Starters and AC Magnetic Motor Starters, commonly known as Motor Starters.

A reduction type starter, wherein an idle shaft is mounted in a starter housing in parallel with a motor shaft and a pinion drive shaft, and an over running clutch is provided on the idle shaft so that a reduction of rotational speed can be performed at two stages.

The starter motor converts: electrical energy into mechanical energy. Technician A says that the direct drive starter doesn’t need an overrunning clutch on its starter drive because it is continuously meshed with the flywheel.

Hence, defining your operating range will help you decide the starter you want. It is always recommended that the starter should not be of shorter range than you want it to be. A starter keeps a check on the engine speed sensing mechanism. It will reflect if there is a problem with the starting of the vehicle.

Unlike direct drive, gear reduction starters use smaller, faster motors to rotate their pinion gears in a roughly 4:1 ratio, which results in lower power consumption and higher torque.

How to Replace a Starter

1. Safety First. Disconnect the battery.
2. Remove the Wiring. Remove the wiring and positive battery cable from the starter solenoid.
3. Remove the Starter and Bolts. Remove the starter retaining bolts.
4. Compare to Verify.
5. Transfer Heat Shield.
6. Replace with New Starter.
7. Secure and Tighten.
8. Connect the Wiring.

When you attempt to start your heavy machinery, you need the engine to start to turn freely as your engine attempts to run. The overrunning clutch in the starter drive makes this happen. So the overrunning clutch transmits torque in one direction but then freewheels in another direction.

Car starters can often look very similar. The problem is there may be small differences that cannot be caught by the eye – the mounting may be different, the gear teeth might not match and will chew up your flywheel, etc. You would be better off installing one known to fit that vehicle and engine.

GEAR REDUCTION. In starters that use direct drive, the armature shaft of the starter motor is attached directly to the drive mechanism. Although “gear reduction” technically takes place between the starter’s pinion gear and the ring gear on the flywheel or flex plate, the pinion gear itself rotates in a 1:1 ratio with the armature shaft.

Power – Direct drive starters require up to 50 percent more electrical power to turn over the car’s engine than do gear reduction starters. This means direct drive requires more current from the car’s battery, larger battery cables are needed and other components are designed to handle higher current.

Two typical designs are Offset Gear Reduction and Planetary Gear Reduction. In the former, the motor armature and Bendix drive are not in-line, whereas in the latter they are lined up.

Gear reduction can be achieved with either spur or planetary gears. Due to the way that spur gears work, starters that use them require an offset armature, which is achieved by placing the starter drive in separate gear housing.