Starter motor ring gears are dimensionally designed on the basis of the following data:
Diameter and tolerance of the shrink diameter
Distance and tolerance between the centre of the flywheel and the starter motor pinion
Pinion dimensions and tolerances:
Outside diameter
Root diameter
Dimension on K teeth
Addendum modification
Number of teeth
Pressure angle
Modulus
The characteristic curves of the starter motor (torque, speed, etc.)
Starter motor ring gears are designed according to certain parameters to guarantee a lifetime (30,000 to 600,000 starting cycles) and a noise level that conform to the manufacturer’s specifications.
Stock and heat treatment
The ring gear transmits torque from the starter motor to the engine crankshaft. The stresses applied to the toothing are defined on the basis of a calculation developed by Defontaine.
As far as centrifugal stresses are concerned, finite element analyses are conducted on the basis of manufacturer-supplied data.
For the design and production of starter motor ring gears, RTE draws up stock specifications and defines the hardening processes best suited to the anticipated use with regard to starter motor torques and engine speeds.
The stock is produced by approved, certified steel mills.
The toothing is quenched and tempered by induction to obtain hardness levels according to the steels selected below. By monitoring the process, all of the significant machine parameters linked to the quality of the hardened zone (depth, hardness, quench cracking, etc.) can be controlled to guarantee a level of Quality that conforms to Automotive standards.
For the design and production of starter motor ring gears, RTE draws up stock specifications and defines the hardening processes best suited to the anticipated use with regard to starter motor torques and engine speeds.
The stock is produced by approved, certified steel mills.
The toothing is quenched and tempered by induction to obtain hardness levels according to the steels selected below. By monitoring the process, all of the significant machine parameters linked to the quality of the hardened zone (depth, hardness, quench cracking, etc.) can be controlled to guarantee a level of Quality that conforms to Automotive standards.
Equivalence to foreign standards
The table below lists the closest equivalent foreign grades to our standard steels.
