The Splines Key

Engineers Rail would like to welcome you to the next phase of our educational adventure, in which I will cover Splines Key.

If you’re looking for the same stuff, then you’ve reached to the appropriate spot.

So, without further fanfare, let’s begin at zero and work our way up.

As you know, A key is a machinery component that connects two power-imparting parts by transmitting torque. So…

Splines key-

Splines are a form of the key which is constructed parallel to the shaft’s axis, known as the splines key. The shaft, which fits in keyways broached in the hub, prepares integrated keys, Known as splined shafts. 

Four, six, ten, and sixteen splines are common in these shafts. Splined shafts are far more durable than single-keyway shafts.

splines key diagram

Types of Splines Key-

There are different types of splines key available-

  • Parallel splines key
  • Involute splines
  • Crowned splines
  • Serrations
  • Helical splines
  • Ball splines

Parallel Splines key-

The sidewalls of the evenly spaced channels are parallel in both radial and axial orientations, known as parallel splines key. Basically, the parallel key is inserted on the shaft. The interaction is provided by sliding the hub over the key.

Involute Splines-

The sides of the evenly spaced grooves are involute, but not as tall as an involute gear. By reducing tensile stress, the curves boost strength.

Short, evenly spaced teeth on involute splines allow for higher strength and more focused tensile properties. Due to their inclination to self-centre, increased structural strength, and simplicity of adjustment to a variety of parameters, they are one of the most often utilised forms of spline shaft.

Read More- Involute Splines- Definition, Types, Materials Selection and Applications

Crowned Splines-

Typically, these splines are involute. These splines can be  Flat root, fillet root, and diameter fit. This form of the spline is used to accommodate angular misalignment between the shaft and the mating component.

The male tooth is “crowned” to achieve this. The crown of the tooth is normally symmetrical around the spline face-width centerline. The tooth thickness is at its greatest at this point.

The tooth thickness steadily reduces as it approaches the ends, with the thinnest parts occurring at each end face. The pitch diameter is used to determine the tooth thickness.

The spline’s outside diameter is usually crowned as well, with the biggest diameter occurring near the thickest tooth thickness and diminishing proportionally to the planned misalignment toward each end face. In most cases, the female spline is not crowned.


This type of spline features a non-involute tooth shape. The male teeth are shaped like an included angle, while the female serration has gaps with the same included angle.

Serrations are commonly utilised on drives with lower diameters where an involute form would not improve strength. Because the teeth are in the form of a simple included angle, more teeth can be placed on a tiny diameter, increasing the contact area.

Serrations are employed in instrument drives, valve shafts, and other applications.

Helical Splines-

These might be in the form of parallel or involute teeth. The lead and helix angles of the helical spline are specified. These splines have a variety of applications.

The helical teeth of the splines slide against each other when the axially fixed member is rotated suddenly. Depending on the rotating direction, this thrusts the axially floating component forward or backwards. Through the use of rotary motion, this form of spline can be utilised to engage or disengage face couplings.

Ball Splines-

A rolling assist spline bearing is the Ball Spline. This is a novel product that uses a ball rolling on a groove attached to the shaft to achieve higher permissible loads than a linear bushing and allows torque transmission while moving linearly.

Ball splines are frequently grouped with recirculating linear bearing guides (also known as linear bushings), although they have advantages over standard linear bushings.

Rotational ball splines integrate linear and rotary motion in one device, whereas standard ball splines provide both linear and torque transmission.

Read also- Ten Different Types of Spring and its Applications

Uses of Splines Key-

Here are the several uses of the splines-

  • Drive Shaft
  • Power take-offs
  • Transmitting torque
  • Aerospace
  • Bi-cycle
  • Aircraft engine


Wrapping Up-

This concludes the Splines key segment for the time being. I hope this has helped you in some way or provided you with some value in return. If so, consider sharing with those in need and bookmarking Engineers Rail for future reference.

Here are a couple of other articles to consider:

Riveted Joints: Definition, Types, Uses, Efficiency, Advantages and More

11 Types of rivets & Their Basic uses with Diagram

Types of Shaper Machine

Thank you being here. I hope to see you in the next segment.

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