Key slot sizes,
Parallel keys[ edit ] "Parallel keys" are the most widely used. These can withstand only torsion of one side of shaft rotation.
Spring pins are an alternative Dutch key component, instead of solid dowel pins. In the absence of approval by the engineer for use of other hole types, standard holes shall be used in high strength bolted connections. This provides a certain amount of play in the holes, which compensates for small misalignments in hole location or assembly, and aids in the shop and field entry of fasteners.
One of the major mounting methods used for connecting such mechanical elements in place is by keys. The Dutch keyways are threaded only on the alternate hub side or shaft side, with a thread clearance hole form on the opposite side.
The various other mechanical elements like gears, cams, sprockets, etc. The advantage of this type of key is that the stress concentration induced due to the key is mahabharata gambling much less. A typical key along with the key seat in both the shaft and the mechanical transmission element is shown below.
Here a circular pin is used in the place of a key. Others[ edit ] A Scotch key or Dutch key features a circular keyway hole instead of rectangularproduced by drilling axially into the assembled hub and shaft, with a metal dowel pin serving as the key. This limited shear strength specification is designed to sustain normal operation, but then give way in the event of excessive shaft torque, thus protecting the rest of the machine from damage.
This type of key is quite similar to the tapered key except for a head which is provided at the bigger end of the key in order to facilitate easy removal of the key. QD quick disconnect bushings work similarly, but place a circular pattern of three unthreaded and three fully threaded holes further out from the shaft axis on a bushing flange, instead of across the bushing-to-hub interface.
Square keys are used for smaller shafts and rectangular faced keys are used for shaft diameters over 6. A Hirth joint is similar to a spline joint but with the teeth on the butt of the shaft instead of on the surface.
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The cross section of the key is either square or rectangular and hence the name. Oversize and Slotted Holes When approved by the engineer, oversize, short slotted holes or long slotted holes may be used subject to the following joint detail requirements: The tapered keys have a rectangular varying cross section.
This type of key tends to have a lesser shear strength than compared to that of a rectangular or square key. The key is a small element whose shape tends to vary based on its type.
The method of calculating the safety of the key for transmitting a particular torque is explained below in the figure.
Hardened washers shall be installed over oversized holes in an outer ply. Types and Designs of Shaft Keys written by: Further due to the tapered section of the key along its length, it acts as an axial retainer for the mechanical power transmitting element.
It consists of a semicircular key seat on the shaft surface which holds the key.
The purpose of the taper is to secure the key itself, as well as, to firmly engage the shaft to the hub without the need for a set screw. Standard holes shall be provided in member-to-member connections, unless oversized, short-slotted or long-slotted holes in key slot sizes connections are approved by the designer.