Gearing And Variable Speed Drives Flashcards
What are the two types of gear drives
Open gear drives and enclosed gear drives
What are gears?
Positive power transmission devices that do not slip
Which gear drive system has more wear and why
The open drive system has more wear because of contaminants
How are you enclosed gear drives lubricated?
By either grease or oil
What is a gear set
Matched pairs of gears manufactured together
What is a gear train?
When two or more gears mesh or work together
What is a pinion?
When two gears have a different number of teeth, the lower number is called the pinion
What is a crown gear?
In a bevel and hypoid gear set, the larger set is called a crown gear or a ring gear
What is drive and driven gear
Drive=power in
Driven=power out
What is direct drive?
When the input and output is the same speed. It is often used to change directions.
What happens when speed is reduced?
The output has an increase in torque. The result is a mechanical advantage
What is an overhung gear?
It has a bearing support on only one side
What is a straddle mounted gear?
Gears that are mounted between bearings
What is a compound gear train?
They have three or more shafts and four or more gears
What is preloading of bearings?
Giving the bearing less than zero axial clearance. This is common with tapered roller bearings in a worm gearbox
What can an increase in backlash be an indication of?
Gear wear
What is a floating gear or shaft?
Where the fear or shaft is allowed to float axially to its best position
Describe how to tell if a helix angle gear is LH or RH
When viewing from the shaft angle, if the teeth point up to the right, it’s a RH and vice versa
Parallel shafts must have what combination of angled gears?
Must use opposite hand gears
Crossing over shafts must have what combination of angled gears?
They must have the same hand gears (such as in a worm gear)
Describe a worm and worm wheel gear set
The worm is the smaller gear, and the worm wheel is is the larger circle gear
What is the drive side of gear teeth?
Most gearboxes rotate in one direction most or all of the time,so the wear is I the drive side of the teeth, and the side that doesn’t make contact is the coast side
What is the addendum?
The top half of the teeth
What is the dedendum?
The bottom half of the tooth
What is the whole depth?
The addendum plus dedendum
What is the clearance?
The space between the bottom land of one gear, and top land of the meshing gear. It allows for lubricant, thermal expansion, and gear runout
What is the working depth?
The addendum, plus the dedendum, minus the clearance
What is the circular pitch?
Also called the gear pitch, it is the distance from the center of one tooth to the center of the next tooth, at the pitch circle
What is the pitch circle?
The diameter, at the pitch circle. It is approximately in the middle of the gear teeth.