Gears and stuff

Gears are used in conjucntion with bearings to..

• change shaft power in gearboxes.

• Transmit power ,change drive directions

• create backlash.

• change power of an idler gear.

Every day spur gears are simple to manufacture and..

• Have helical teeth that don`t mesh.

• The larger wheel is called the pinion.

• Have straight teeth parallel to the axis of the shaft.

• Have straight teeth at right angles to the shaft.

Like spur gears, helical gears also connect parallel shafts but..

• Carry lighter loads at slower speeds

• Have their teeth cut at an angle or helix to the shaft.

• Have their teeth cut at an angle and do not require thrust bearings.

• Have their teeth cut in a V pattern and do require a thrust bearing.

Double helical or Herringbone gears are designed to..

• Unbalance the thrust forces and eliminate the need for a thrust bearing.

• Have Y shaped teeth that require a thrust bearing.

• Balance the thrust forces and eliminate the need for a thrust bearing.

• Run on a rack and pinion.

Bevel gears are used..

• Between parallel shafts.

• Only use part of the rotation.

• On a linear rack.

• Between intersecting shafts.

Bevel gears with curved teeth ..

• Are noisier but carry lighter loads than straight or spur bevel gears.

• Are quieter, smoother and carry greater loads than straight or spur bevel gears.

• Can carry radial loads only.

• Used on parallel shafts.

Hypoid gears..

• Axis of the shafts are in the same plane and intersect.

• Connect intersecting shafts.

• Have a light contact and do not require lubrication.

• Axis of the shafts are not on the same plane and do not intersect.

The speed ratio of Worm gears is calculated by..

• Multiplying the number of teeth on the wheel gear by the teeth on the worm wheel.

• Dividing the number of teeth on the straight cut gear by the number of teeth on the pinion gear.

• Dividing the number of thread starts on the worm-screw into the the number of teeth on the worm-wheel gear.

• Multiplying the number of straight teeth on the worm wheel by the number of teeth on the Worm gear.

Worm gears..

• Offer high reductions in multiple steps,quiet and can only carry light loads and very efficient to other gears.

• Are noisy and carry light loads.

• Are very efficient compared to other gears.

• Offer high reductions in single steps,quiet and carry heavy loads but inefficient compared to other gears.

How are reduction gears classified?

• The number of teeth in the pinion gear.

• Number of teeth on the large (wheel or Bull) gear

• The number of steps used to bring about a reduction.

• The speed at which the propeller is slowed down,