Gears

Pitch of a gear

THE DISTANCE BETWEEN two identical points on two adjacent gear teeth. Ideally, it is measured at the pitch line

4 categories of Gears on axis'

1.)Parallel Axes / Spur Gear, Helical Gear, Gear Rack, Internal Gear 2.)Intersecting Axes / Miter Gear, Straight Bevel Gear, Spiral Bevel Gear 3.)Nonparallel, Nonintersecting Axes / Screw Gear, Worm, Worm Gear (Worm Wheel) 4.)Others / Involute Spline Shaft and Bushing, Gear Coupling, Pawl and Ratchet

Helical Gear

A cylindrical gear with teeth in the shape of spirals. They have better teeth meshing than spur gears and have superior quietness and can transmit higher loads, making them suitable for high speed applications. When using helical gears, they create thrust force in the axial direction, necessitating the use of thrust bearings. Helical gears come with right hand and left hand twist requiring opposite hand gears for a meshing pair.

Gear Rack

A rotating gear that meshes with a bar that has gear teeth along its length. It changes rotating motion into linear motion. Either helical/straight tooth racks

Spur Gear

A wheel-like disk with teeth cut along the outside rim, all teeth being parallel to the axis of rotation. It is the most common of its type.

Bevel Gear

Bevel gears have a cone shaped appearance and are used to transmit force between two shafts which intersect at one point (intersecting shafts). A bevel gear has a cone as its pitch surface and its teeth are cut along the cone. Kinds of bevel gears: straight bevel gears, helical bevel gears, spiral bevel gears, miter gears, angular bevel gears, crown gears, zerol bevel gears and hypoid gears.

Rack and Pinion Gear

Gear system that changes rotational motion to linear motion

Internal Gears

Internal gears have teeth cut on the inside of cylinders or cones and are paired with external gears. The main use of internal gears are for planetary gear drives and gear type shaft couplings.

Herringbone Gear

They neutralize side thrust by having two helical-gear halves, one having a right-hand and the other a left-hand helix. Used for transmitting power between parallel shafts. It was developed to overcome the disadvantage of the high-end thrust that is present with single-helical gears.

Worm Gear

gear consisting of a shaft with screw thread (the worm) that meshes with a toothed wheel (the worm wheel)

Gear Ratio

the ratio of output turns to input turns for a pair of gears

Spiral Bevel Gear

• Teeth of a bevel gear are inclined at an angle to the face of the bevel • Have overlapping teeth Due to higher tooth contact ratio, they are superior to straight bevel gears in efficiency, strength, vibration and noise.

Miter Gear

Miter gears are bevel gears with a speed ratio of 1. They are used to change the direction of power transmission without changing speed. There are straight miter and spiral miter gears. When using the spiral miter gears it becomes necessary to consider using thrust bearings since they produce thrust force in the axial direction.

Screw Gear

Screw gears are a pair of same hand helical gears with the twist angle of 45° on non-parallel, non-intersecting shafts. Because the tooth contact is a point, their load carrying capacity is low and they are not suitable for large power transmission.

Gear vs. Sprocket

Simply said, a gear meshes with another gear while a sprocket meshes with a chain and is not a gear. Aside from a sprocket, an item that looks somewhat like a gear is a ratchet, but its motiion is limited to one direction.