Products > Splines


Internal Spline produced by Arrow Gear
Internal spline on a spur gear

Splines are another type of parallel axis component manufactured by Arrow Gear.

A spline is similar in appearance to a spur gear. However, as a gear transmits motion between two shafts, splines only apply the transmission of power on the same axis.

While gears can be configured in a) both external, or b) one external and one internal, splines are always used in a combination of one external and one internal. Both splined members have the same number of teeth with the internal member sliding on to the external member. The most typical location for a spline is on the end of a shaft type part, but they can also be located inside the bore of a part.

Involute Splines produced by Arrow Gearr
Fig. 1 - Involute splines

Arrow produces three types of splines which are detailed as follows.

Involute Splines
With involute splines, the term “involute” describes the shape of the tooth that is cut. Spur and helical gears also have involute shapes on their teeth. In fact, the involute spline could be considered to be a spur gear with different dimensional proportions. See Figure 1.

Serration Splines produced by Arrow Gearr
Fig. 2 - Comparison of Involute and Straight Sided Serration Splines

Straight Sided Serration
A straight sided serration is similar to the involute spline except that the side of the tooth is a straight surface and not an involute curve. The shape of the tooth is triangular. A serration is a type of spline and can be made externally or internally. See Figure 2.

Straight Sided Spline
The straight sided spline has teeth that look like several keys arranged around the part. The sides of an individual tooth are parallel to each other. Like the other parts previously mentioned, they can be made externally or internally.
See Figure 3.

Straight Sided Splines produced by Arrow Gearr
Fig. 3 - Straight Sided Splines - Internal and External

Internal splines are typically manufactured with shaping equipment or broached, while external splines can either be produced with shaping or hobbing equipment, based on the geometric parameters of the specific part.

Arrow’s size range and capabilities for Splines are provided in the list below.

External Spline produced by Arrow Gear
External spline on the shaft of a bevel gear

Maximum Pitch Diameter – 32”
Diametral Pitch – 4/8 – 80/160
Face Width – 13.0
Unground Tooth – AGMA Q9
Ground Tooth – AGMA Q13