Study guide Flashcards
Why should a key sit tight?
Otherwise it rocks back-and-forth under load and damages to the shaft and hub
What should the width of a square or flat key be.
1/4 of the diameter
Pratt & Whitney key
Also known as the buried key, these keys are used when the hub slides back-and-forth on the shaft. Rounded edges make it easier to align
Woodruff key
Light applications.  First two digits are 1/32 in the last two is the diameter in 1/8
Gib head key timing key
For transmitting, heavy loads, come in parallel or tapered. There needs to be a gap between the gib head and hub.
Quick detachable bushing
Used for gear, reducers, hubs, sprockets, and pulleys and line. Boring drives.  Has an axial split through the barrel and flange. Only one key.
Split taper bushing
Only has a split in the barrel, and it is internally and externally keyed
Taper lock bushing
Uses supplied set screws for assembly and disassembly
Locking in positioning devices
Set screws, tab washers, and shear pins
Set screws are the most common. Tab washers are for bearing installation where a positive location is important.
RingFetter no key
Has a double tapered, thrust ring to locate and lock hubs and gears on the shaft. Do not use them for cast-iron.
Types of chain couplings
Roller chain, silent,, synthetic chain
Roller chain coupling
 Comes in single and double
Double is the most common they are made of high tensile heat, treated steel the teeth are Harden for maximum where 
Which roller chain provides more end float
The single strand, because of an absence of a pin link and roller link plates in the centre of the chain.
Silent chain
Recommended for heavy duty drives at speeds up to 5000 RPM. It is wrapped around two wide sprockets.
Advantage is it can perform smoothly and quietly, and remain in balance at high rotational speed
Synthetic chain coupling
They are for light power transmission drives. Made of plastic or nylon. They’re usually used where it’s not desirable to have oil or grease lubricant, contaminated, and manufactured products.
synthetic chain info
 No lubrication needed, and are non-conductive. Suggested to use in corrosive conditions if the pins are made of stainless steel. Some torsional flexibility due to synthetic material.
Gear coupling
The gear teeth in the outer cover mesh with the teeth of the two hubs. The cover is straight sided, and the teeth and Hubs are involute. Curved
Double universal joint
Used if there is deliberate, angular, or parallel, offset misalignment between the driver and driven machine
Double universal joint
They do not produce the same speed fluctuations as a single universal joint if angles are equal at each joint.
Universal joint
The weakest part is the cross is made of harden steel with bushings or needle bearings fitted for a yoke. The bushings must be lubricated for long wearing reliability.
Fluid couplings
The impeller sometimes referred to as a pump and the turbine, which also can be called the runner
Impeller and turbine
Fluid coupling
The impeller/pump has a series of radial blades.
The turbine/runner is the output and has a series of radial blades
Do the impeller and turbine blades face each other
Yes
Fluid couplings
They use feasible plugs that melt if an overload continues. when the coupling slips too much, it generates excess friction from the churning oil. This causes the fuesable plug to melt.
If fusible plug melted should be replaced with?
One with the correct melting temperature. Do not replace it with a steel plug.
Tapered hub installation
Find out from the manufactures installation procedure how far it should go on the shaft.
Tapered hubs
Some are pressed on or expanded hydraulically. This is done by pushing or pulling the hub on the shaft At the same time injecting oil between the coupling in shaft.
Tapered hubs
 Measure the install position after it is cooled with a micrometre
Square Jaw clutches
Lock in to mating recesses.
These clutches are bi directional, one jaw is splined or keyed, and the other can move axial to engage with other 
Square JaW
Can only be engaged at very slow speeds, but can be disengaged at any speed as long. It is not transmitting high torque. Engagement of a square jaw clutch at higher speeds can damage the jaws shear the keys, splines and twist the shaft.
Spiral jaw clutches
Can be engaged at a higher speed in square, jaw, but still will cause shock to load at engagement
Square JaW
Usually engaged by shifting levers
Spiral JaW
Operates in one direction only, rotation in the opposite direction causes clutch to disengage.
Multiple tooth
Uses a large number of small gear, teeth, or serrations to provide engagement.
 1/2 of the clutch must be free to slide on the Key or spline to allow for engagement
Actuation method is most often buy electric solenoid
Eddy current clutches SLIP
Have soft, iron rotors,
Slip is required to develop torque on Eddie currant clutches.
The output torque is direct function of the strength of the electromagnets and the amount of slip
Cam type , sprag clutch
Have two races that are very smooth and hard, between these two members are spring loaded cams/sprags. They lean in one direction and are held in place by a spring retainer.
Sprag
If the inner race attempts to rotate clockwise at a higher rpm than the outer race, the cams lock up in the power from the inner is transferred to the outer.
Eddy current brakes
The stater or rotor is anchored. This type of brake works purely on electrical principle of the repulsion of same poles
Radial friction clutches
Expanding shoe clutch
Contracting shoe clutch
Axial friction clutchS
Single friction
Multiple disc
Cone clutch
It is a cross between a radial and axial clutch.  Con wedges, provide a mechanical advantage, due to the wedge in the drum. 
To make disengagement possible angles are kept from 10 to 15° 
They can be used where they are submerged in oil, and then some applications were friction surfaces are metal.
Types of gears.
Spur
Helical gear herringbone gears,
bevel gears, worm gears Non metallic
Working depth
This equals addendum plus the dedendum minus the clearance 
Whole depth
The height of the whole tooth, which includes addendum plus the dedendum
Circular pitch, or gear pitch
Centre of tooth to centre of next at the pitch circle
Pitch circle
Approx the middle of the theeth
Pressure angle
Angle between line of action. 20-14 1/2 most common
Diametral pitch
Number of teeth divided by pitch
Gear ratios
Driven divided by drive
Shaft position
Parallel
Intersecting
Crossings over
Mitre gears
Are bevel gears intersect at 90
Zerol bevel
Has no axial thrust
Hypoid
Bevel gear. crossover Larger pinnon. Thrust in either direction
Hypoid
Needs ep oil. Straddle mounted
Planetary gear
Sun
Carrier
Ring
Backlash
Is the clearance between gear teeth at pitch line
Tensile members
Consist of cords that carry the load
What are the parts to a belt?
Top is the cover, load, carrying section are the tensile members, middle, bottom is the compression section.
Pitch line
Pitch line runs through the load carrying zone of the belt where the tensile members are located
Which belt has an uncovered sidewall
Cogged RAW edge
How is a Cogged RAW edge designated?
AX, Bx and CX they are precision, ground for better fit, and grip
Banded belts, they are also called joined classical belts
The B C D cross-sections are readily available alignment is critical, because these belts have less ability to flex sideways than individual belts
Banded belts
 They were developed to solve problems of belt vibration, whip, and turnover
Fractional horsepower belts
2L, 3L,4L and 5L
Generally used on drives less than 1 hp but some manufacturers offer them with ratings up to 17 hp
Open ended
They are in a, B, C, D or E with VO at the end
Limitations of open ended belts
They can only carry 1/3 of a load of a corresponding endless belt
Miter gear
1~1 intersections at 90
Hypoid
Shaft is off centre. Large contact area
Speed increaser
Large gears drives small gear
Internal gears have
More tooth contact
As the angle of the heilix increases
Sliding friction and thrust increases
Ratio
Driving divided by driven
How not to check the mesh pattern on worm wheels
Do not use Layout blueing
Where would you put the blue?
Drive end the shaft
What happens if you use too much bluing
Poorly formed mesh patterns on the meeting teeth
What is mesh pattern?
The contact area between two meeting teeth of two gears as one transfers power to the other
What is the side of the driven tooth called?
Active or drive side flank
Backlash
 Backlashes the rotational arc of clearance between a pair of mounted gears
Backlash can?
Cause noise, overloading, overheating of gears and bearings, and even seizure and failure.
Why is backlash necessary?
To prevent damage by tooth interference
When is the minimum backlash required?
For applications, involving frequent, starting, and stopping/reversed, rotation, or a load
Where is backlash measured?
At the pitch circle
How can you check backlash?
Using a dial, using lead wire, using a feeler gauges manually fitted between mating gears
What is held stationary when checking backlash?
The worm/shaft
External backlash check
To be done with lines at the same radius
Tire rods or torque arms
Are to prevent rotation of the gearbox, and must be mounted in the position that allows the gearbox oil levels to be checked 
Where to install a tie rod or torque arm
90° angles between output in point of torque arm attachment
For larger units such as conveyor drives
A spring mountain torque arm would be used, this arm takes up, torsional shock.
What is necessary with lubrication?
Oil dams, or oil circulation paths, they are to reduce wear on bearings and gears.
What are scrapers for?
They are device mounted close to the sides of the pinion gears. The scrapers do not touch, but they scrape excess oil off the gears. They collect and direct oil to the passageways leading to the bearings.
What happens to copper tube and fittings?
They get work hardened from vibration and pressure pulstations
Couple ways you can check oil levels
Watch dog is designed for bearing housing and gearboxes.
Visual site level indicator. Downfall of this one discolouration can incorrectly be taken as oil in the unit.
Roller chain properties
Consists of two basic types of links, which are pin links, and roller links
What is a connecting link?
A connecting link consists of pin link with pins that are drilled for cotter pins. Or grooved at their outer ends for a spring clip. Pins are usually used on number 80 chains or larger.
How do you assemble an offset link?
Hold the pin so that it’s flat is aligned with the flat side of the hole in the side plate before you install the pin.
Which chain is general purpose?
Standard single strand, roller chain
Silent chain or timing chain
Consists of links, made up of tooth plates
Silent chains are used for
Transmitting high horsepower in a small space. High speed drives and precision timing.
Where would you find a hunting link?
On a silent chain, it is used when an odd number of pitches is required.
How to join a silent chain
A joining pin, or connecting link is used to change the length by two pitches.
What are the three silent chain designs
Side guides, centre guide, and duplex
Duplex is for serpentine drives 
Silent chain parts
Centre guide, tooth link, pins, and bushings
This design offers the highest efficiency, the widest range of speeds in the widest range of load Capacity
What happens if you have too much chain tension?
Reduce life, chain and sprocket
Overloading of bearings and driver and driven units. 
What happens with to little tension?
Chain whip and vibration
Chain can wrap up on one of the sprockets
Chain tension for medium speed drives
4 to 6%
Chain tension for high speed and vertical drives
2 to 3%
How can chains be tensioned?
Adjustable centers, or tightening idlers
Chain lubrication methods
Manual or drip, bath, and forced
Where to apply the oil on a multiple strand chain
On the inside of the lower span, this forces oil into the chain by centrifugal force
Manual or drip feed lubrication
It is intended for low speeds under 600 ft./min.
When do you discard a chain?
If it is elongated by 3% or more
What are the two ways to check elongation
Measure it when it’s totally stretched, or lay it beside a new chain, and note the difference in length
What should you do if a chain has been subjected to excessive load for any reason
You should replace the chain
What does the wrap angle depend on with sprockets?
The wrap angle on a small sprocket is smaller when the ratio is larger
Centre distance between sprockets
What must a wrap angle be?
120°
However, an angle can go as low as 90° if proper chain tension is closely monitored
Inspection of chains and sprockets
If an unusual noise occurs, ensure the chain is getting enough lubrication. You might have to apply lubricant manually
Open ended belt construction
Strong envelope for a good fastener retention

multiple ply square woven fabric tension members provide reinforcement for cushion
Tear resistant breaker fabric
Where would you find an open ended belt
Where and this belts are difficult or impossible to install.
They may be used in emergencies for replacements when the exact length of endless belt is not available
Limitation of open ended belts
They can only carry 1/3 of the load of a corresponding endless belt
They cannot be used with endless belts in multi belt drives
Installation of V belts
Needs to be installed correctly to attain maximum belt life
What can happen if dirt or deposits get on the belt or sheave
They degrade the belts and sheaves through abrasion and corrosion
They also produce an imbalance in rotating sheaves
What is the main reason for cleanup
Of sheaves
To inspect for possible cracks, especially around the hub and to ensure dynamic balance.
Where should you not use an idler pulley?
On reversing devices
What does an outside idler pulley do?
It provides means of tensioning your belt.
It uses a flat pulley that is at least 1.5 times the diameter of the smaller pulley
What do inside idlers do?
Decrease the ark of contact
What should you use for an inside idler?
If possible, use a groove, pulley, as it provides better tracking
Where to place an inside idler
As far from the pulley that the belt travels towards in order to prevent unequal arc of contact.
Where would you find belt whip?
Long spans.
Where do you place a contact idler
1/3 of the span distance from the larger pulley on the slack span
Outside idler goes to the left of the slack side. Driven side.
Inside idler goes to the right of the slack side Driver side
Synchronous belts are also called
Positive drive belt or timing belts
What were timing belt used for?
For drives that could not tolerate any slippage. Alignment needs to be tits.
What is a pitch of a timing belt or anything for that matter
The distance from one tooth on the belt to a corresponding point on the next tooth
What is a disadvantage of synchronous belt drives
Standard neoprene belts do not meet the static conductivity requirements for operation in explosive environments.
Synchronous belt, drive efficiency
98%
What is a pulley
A pulley is a wheel used to transmit power from its rim to a belt
What is a sheave?
A sheave is a pully with a groove that runs around the circumference of a rim. Use the a belt on this type of pulley
What is a sprocket?
It is a pully with grooves running across the rim
Types of sprockets
Flanged, sprocket and unflagged sprocket
And an eagle sprocket, they have their own coding system
Gearbox types
Open gear drives, enclosed gear drives,
What are open gear drives good for?
They are suitable for light. Duty drives are in a situation where sealing the gears from the elements is difficult or impossible.
They tend to be slower moving large gears with larger than normal clearances
Enclosed gear drives
When everything is enclosed to protect from outside elements, such as dirt, water, and particles. They can have either oil or grease lubrication.
What is the addendum?
Radial distance from the pitch circle to top of the land of the tooth
Dedendam
The radial distance from the pitch circle to the bottom end of the tooth
Narrow belt drives
Narrow series,V belt drives can be fixed centre drives in which the drives and driven units cannot be adjusted closer or further apart.
Centring sheave, both sides of the Sheave move in or out.
Non-centering shave, only one side moves. The side away from the hand wheel
Wet disk drives
Constant input speed usually 1760 RPM and an output speed of 0 to 760 rpm.
Output/male , spline teeth are on the rim
input spline teeth are inside. Made of sintered bronze material.
Variable fill, or scoop tube
They very speed, and Power By changing the amount of oil contained in the rotating case
They have an impeller and turbine and the scoop tube.
Scoop tube position determines the oil charge level.
Torque converter location
Torque converter type units are usually bolted directly onto the internal combustion engine flywheel’s
Parts to the torque converter
Fluid impeller attached to the engine flywheel delivers large quantities of hydraulic fluid at high speeds into a turbine that is forced to rotate and deliver power 
Torque converter operation
The oil leaving the impeller at high speeds, directed to the turbine, where it is, then redirected into the stator
The impellers also called a pump
The turbine is also called the follower
What is a gear train with three or more shaft called
A compound
Which side of the gear is always in contact
Drive side
Type of tooth profile that is not straight cut
Involute
Gearing, system requiring one gear to be floating on the shaft
Herringbone
The angle between the lines of contact on a gear system
Pressure
The device that controls the power transmission in a fluid clutch
Scooptube
Two types of clutchS that slip during engagement
Fluid and friction
Type of positive clutch that is one directional
Spiral JaW
Types of gearboxes
Single reduction gearbox, has two shafts and two gears
Double or multiple reduction these have at least three shafts in four gears due to stages of reduction. The years do not have to be radically different in diameter.
What is more efficient? belts or chains
Chains
