Key Slot Shaft
Posted By admin On 01/04/22One of the major mounting methods used for connecting such mechanical elements in place is by keys. A shaft key always requires a key seat both on the shaft as well as on the mechanical element. A typical key along with the key seat in both the shaft and the mechanical transmission element is shown below.
Why Power Transmission Shafts Have Both Keys and Keyways
One part of the key fits into a precut slot in the shaft known as a key seat. The remainder slides into a groove in the hub called a keyway. Woodruff keys are flat, semicircular keys that rock into place and adjust to an angular spine without coming unseated. Machine keys are elongated, with either rounded ends, square ends, or tapered gib heads. The shaft is usually key slotted for the full length for the shaft or slotted from the end of the shaft and along the length of the shaft for a distance greater than the length of the key to be used. Parallel keys can be installed by lining up the keyslots in the shaft and the component and then pressing the parallel key between the slots.
Short answer: Keys and keyways prevent the shaft from rotating on the bore and can assist in torque transmission between the two connected shafts.
Sometimes understanding the small details, help us understand the big picture. On this blog we will dive into some basic concepts of power transmission.
Have you tried to start an engine, or put a drive train into gear, and nothing happened?
You may have even heard the starter motor engage and start, but then there was no forward motion when the transmission finally became engaged. Most of the time, when this occurs, there are a few things that you can check, such as the transmission fluid, transmission shift cable, or the transmission shaft key. But, let me explain this a bit further.
Breaking down the components
Power transmission
As the term easily implies, power transmission is the transfer of energy from a place of generation to a place where it is applied to perform useful work. In Figure 1 below, you can see how a steam turbine transfers the power generated by steam into a generator, which in turn creates electricity. Note the shaft connecting the steam turbine with the generator. Power generation is one of the many industries covered by Lovejoy products.
(Figure 1)
Shaft
A shaft is an element used to transmit both the power and torque. Shafts are made in a variety of different shapes and forms, but most tend to have circular cross sections that are either solid or tubular shaped. Shafts transmit power directly from a driving device or power source into a load (figure 1). Shafts can carry gears, pulleys, and sprockets in order to transmit rotary motion and power via mating gears, belts, and chains. Alternatively, a shaft may simply connect to another shaft via a coupling mechanism. Couplings are connected to a shaft by means of a key, keyway, or keyseat.
Key, Keyway, and Keyseat
A key is a piece of metal used to connect a rotating machine element to the shaft. A key prevents a relative rotation between the two parts, and may enable torque transmission to occur. For a key to function properly, both the shaft and rotating elements (gear, pulley and coupling) must have a keyway and a keyseat. Usually the term keyseat is referred as a groove or pocket on a shaft, and a keyway is a slot in a hub in which the key fits into. The complete system is called a keyed joint (Figure 2).
(Figure 2)
Keys are made of varied types of materials, and also come in different shapes and sizes. The most common key shapes are rectangular or tapered, and are typically made of steel.
Mechanics
In order to lock a hub or bushing and shaft together, and also to prevent a shaft from rotating in the bore (Figure 2), a key is commonly inserted into a keyway that is machined in both the bore and the shaft. The key is responsible for preventing any rotation between the shaft and the bore, and also carries a portion of the torque load to the keys. Torque transmission by keys is the most common and widely used power transmitting method. Unfortunately, misaligned keys and keyways can result in mechanical failures. Therefore, in order to ensure an appropriate fit, the width and height dimensions of a standard key and keyway must adhere to recommended tolerances. Industry standards for key sizes in various bores exist for both the English and Metric systems.
In addition, when there is a distance that exists between the driving and driven components, drive shafts frequently connect with one another using one or more universal joints, jaw couplings, or in some cases, a splinted joint or prismatic joint.
So, to conclude, the two most important functions of keys and keyways on a power transmission shaft are to:
- Prevent the shaft from rotating in the bore
- Enable power transmission through the torque
In this article we will see the basic difference between slot , holes, groove, and keyways.
1. Hole: circular cutout, either through the material or to a blind depth.
Types of Hole :
They are different types of holes that are mentioned below.
1.Simple Hole
2.Counter board
3.counter sunk
4.Tapered
5.counter drilled.
2. Slot or Slotted Holes: an elongated hole. It is stretched in one direction but still has full radii on the ends. A slot is cut into a flat plate or normal to the axis of a cylinder.
Slot Hole Design Consideration :
Slotted holes are widely used in most sorts of mechanical design. Apply mainly in precisely fine-tuning for uncontrollable dimensions beforehand, alignment accuracy, fixation in certain direction meanwhile keeping slipping free in other directions, and so on. Such as tension device of belt pulley, thermal stress protection for slender bar structural parts or long spindle shafts, alignment accuracy in complex dimension chain, a mechanism for enhancing tolerance, and eliminating accumulated error.
In mechanical design, some principles and factors we should take into account include the shape and travel of the slotted holes, the structural strength affected by the holes, and so on. In actual application, they can be classified into the following types: singleton slotted holes, coupled slotted holes.
Slotted Holes Slotted holes can be dimensioned in several different ways.
a. Center points on the longitudinal axis are located and the radii are indicated with a note.
b. Linear measurements indicate the overall size of the slot and the radii are specified.
c. A note indicates the two linear dimensions of the slot and another note specifies the radii.
Choose the most appropriate technique for sizing the slotted hole. The technique used for sizing the slot determines how the slot is located.
See Also: What is Slotting Machine- Principal parts of Slotter Machine
3. Groove:a groove is a cylindrical slot. Grooves are cut around the OD or ID of a cylinder and do not pass through the axis of the cylinder.
You can simply understand that a slot can be through or blind but a groove is always blind.
In manufacturing or mechanical engineering a groove is a long and narrow indentation built into a material, generally for the purpose of allowing another material or part to move within the groove and be guided by it.
Examples include:
Keyway Slot On Shaft
- A canal cut in a hard material, usually metal. This canal can be round, oval or an arc in order to receive another component such as a boss, a tongue or a gasket. It can also be on the circumference of a dowel, a bolt, an axle or on the outside or inside of a tube or pipe etc. This canal may receive a circlip an o-ring or a gasket.
- A depression on the entire circumference of a cast or machined wheel, a pulley or sheave. This depression may receive a cable, a rope or a belt.
- A longitudinal channel formed in a hot rolled rail profile such as a grooved rail. This groove is for the flange on a train wheel.
4. Keyway:
Shaft Key Slot
In mechanical engineering, a key is a machine element used to connect a rotating machine element to a shaft. The key prevents relative rotation between the two parts and may enable torque transmission. For a key to function, the shaft and rotating machine element must have a keyway and a keyseat, which is a slot and pocket in which the key fits. The whole system is called a keyed joint.
Read More: Types Of Mechanical Keys- Design Of Keys.