Please select the most suitable products by carefully considering the characteristics of items and contents of the product tables.
It is also important to read all applicable notes before the final selection.
1. Caution in Selecting Mating Gears
KHK stock internal gears can mate with any spur gears of the same module, however, there are cases of involute, trochoid and trimming interference occurrences, depending on the number of teeth of the mating gear.
Various types of interference and their symptoms and causes are tabulated below, also shown, the number of teeth of allowable mating pinions.
Interferences and the Symptoms
TYPE
SYMPTOMS
CAUSES
Involute interference
The tip of the internal gear digs into the root of the pinion.
Too few teeth on the pinion.
Trochoid interference
The exiting pinion tooth contacts the internal gear tooth.
Too little difference in number of teeth of the two gears.
Trimming interference
Pinion can slide in or out axially but cannot move radially.
Too little difference in number of teeth of the two gears.
Allowable Mating Pinions and Number of Teeth
No. of teeth of Internal Gear
No. of teeth of Allowable Mating Pinions
Lower limit No. of teeth by Involute interference
Upper limit No. of teeth by Trochoid interference
Upper limit No. of teeth by Trimming interference
50
22
41
33
60
21
51
43
80
20
72
64
100
19
92
84
120
19
112
104
160
19
152
144
200
18
192
184
Established equipment and technology. Custom Gears are also available.
Diameter Ø700mm maximum, Module 6.5 maximum, Cutting Stroke 170 mm
2. Caution in Selecting Gears Based on Gear Strength
The gear strength values shown in the product pages were computed by assuming a certain application environment.
Therefore, they should be used as reference only. We recommend that each user computes his own values by applying the actual usage conditions.
The table below contains the assumptions established for these products in order to compute gear strengths.
Catalog No. Item
KSI
KSIR
Calculation Assumptions for Bending Strength of Gears
Formula NOTE 1
Formula of spur and helical gears on bending strength (JGMA401-01)
No. of teeth of mating gears
30
Rotation
100rpm
Durability
Over 107cycles
Impact from motor
Uniform load
Impact from load
Uniform load
Direction of load
Bidirectional
Allowable beam stress at root σFlim (kgf/mm²) NOTE 2
19
Safety factor SF
1.2
Calculation assumptions for Surface Durability (Except where it is common with bending strength)
Formula NOTE 1
Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant
100cSt (50°C)
Gear support
Symmetric support by bearings
Allowable Hertz stress σHlim (kgf/mm²)
49
Safety factor SH
1.15
Note 1: The gear strength formula is based on JGMA (Japanese Gear Manufacturers‘ Association) The units for the rotational speed (rpm) and the stress (kgf/mm2) are adjusted to the units needed in the formula.Note 2: The allowable bending stress at the root σFlim is calculated from JGMA401-01, and set to 2/3 of the value in the consideration of the use of planetary-, idler-, or other gear systems, loaded in both directions.
In order to use KHK stock internal gears safely, read the Application Hints carefully before proceeding. Also "1. Caution on Performing Secondary Operations>", "3. Notes on Starting Operations" and "4.
Other Points to Consider in Applications" in the Spur Gear KHK Technical Section should be consulted.
1. Point of Caution in Assembling
a KHK stock internal gears are designed to give the proper backlash when assembled using the center distance given by the formula below. The amount of backlash is given in the product table for each gear.
a =
d2 - d1
Where a : Center Distance d1 : Pitch Diameter of Pinion d2 : Pitch diameter of internal gear
2
Note that the direction of rotation of the internal gear is different from that of two spur gears in mesh.
To use as a planetary gear drive, the following conditions must be satisfied.
(646) 396-GEAR
