External meshing deceleration starter, the deceleration mechanism uses idler gear as intermediate transmission between the armature shaft and the starter drive gear, and the electromagnetic switch iron core and the drive gear are coaxial, and directly push the drive gear into meshing without the need for a fork. Therefore, the shape of the starter is quite different from the ordinary starter. The transmission center distance of the external meshing deceleration mechanism is relatively large, so it is limited by the starting mechanism, and its deceleration ratio cannot be too large, generally not greater than 5, and is mostly used in low-power starters.
The internal meshing deceleration starter has a small transmission center distance of the deceleration mechanism and can have a larger reduction ratio, so it is suitable for a larger power starter. However, the internal meshing deceleration starting mechanism is noisy, and the drive gear still needs to be moved by the fork to engage, so the shape of the starter is similar to that of the ordinary starter.
The planetary gear type deceleration starter has a compact structure. Large transmission ratio and high efficiency. Since the output shaft and the armature shaft are coaxial and have the same rotation direction, the armature shaft has no radial load, and the vibration is small, so the overall size is small.