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Millwright 2 > Study guide > Flashcards

Study guide Flashcards

1
Q

Why should a key sit tight?

A

Otherwise it rocks back-and-forth under load and damages to the shaft and hub

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2
Q

What should the width of a square or flat key be.

A

1/4 of the diameter

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3
Q

Pratt & Whitney key

A

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

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4
Q

Woodruff key

A

Light applications.  First two digits are 1/32 in the last two is the diameter in 1/8

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5
Q

Gib head key timing key

A

For transmitting, heavy loads, come in parallel or tapered. There needs to be a gap between the gib head and hub.

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6
Q

Quick detachable bushing

A

Used for gear, reducers, hubs, sprockets, and pulleys and line. Boring drives.  Has an axial split through the barrel and flange. Only one key.

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7
Q

Split taper bushing

A

Only has a split in the barrel, and it is internally and externally keyed

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8
Q

Taper lock bushing

A

Uses supplied set screws for assembly and disassembly

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9
Q

Locking in positioning devices

A

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.

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10
Q

RingFetter no key

A

Has a double tapered, thrust ring to locate and lock hubs and gears on the shaft. Do not use them for cast-iron.

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11
Q

Types of chain couplings

A

Roller chain, silent,, synthetic chain

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12
Q

Roller chain coupling

A

 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 

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13
Q

Which roller chain provides more end float

A

The single strand, because of an absence of a pin link and roller link plates in the centre of the chain.

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14
Q

Silent chain

A

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

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15
Q

Synthetic chain coupling

A

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.

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16
Q

synthetic chain info

A

 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.

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17
Q

Gear coupling

A

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

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18
Q

Double universal joint

A

Used if there is deliberate, angular, or parallel, offset misalignment between the driver and driven machine

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19
Q

Double universal joint

A

They do not produce the same speed fluctuations as a single universal joint if angles are equal at each joint.

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20
Q

Universal joint

A

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.

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21
Q

Fluid couplings

A

The impeller sometimes referred to as a pump and the turbine, which also can be called the runner

Impeller and turbine

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22
Q

Fluid coupling

A

The impeller/pump has a series of radial blades.

The turbine/runner is the output and has a series of radial blades

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23
Q

Do the impeller and turbine blades face each other

A

Yes

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24
Q

Fluid couplings

A

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.

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25
Q

If fusible plug melted should be replaced with?

A

One with the correct melting temperature. Do not replace it with a steel plug.

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26
Q

Tapered hub installation

A

Find out from the manufactures installation procedure how far it should go on the shaft.

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27
Q

Tapered hubs

A

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.

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28
Q

Tapered hubs

A

 Measure the install position after it is cooled with a micrometre

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29
Q

Square Jaw clutches

A

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 

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30
Q

Square JaW

A

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.

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31
Q

Spiral jaw clutches

A

Can be engaged at a higher speed in square, jaw, but still will cause shock to load at engagement

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32
Q

Square JaW

A

Usually engaged by shifting levers

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33
Q

Spiral JaW

A

Operates in one direction only, rotation in the opposite direction causes clutch to disengage.

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34
Q

Multiple tooth

A

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

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35
Q

Eddy current clutches SLIP

A

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

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36
Q

Cam type , sprag clutch

A

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.

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37
Q

Sprag

A

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.

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38
Q

Eddy current brakes

A

The stater or rotor is anchored. This type of brake works purely on electrical principle of the repulsion of same poles

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39
Q

Radial friction clutches

A

Expanding shoe clutch

Contracting shoe clutch

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40
Q

Axial friction clutchS

A

Single friction

Multiple disc

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41
Q

Cone clutch

A

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.

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42
Q

Types of gears.

A

Spur
Helical gear herringbone gears,
bevel gears, worm gears Non metallic

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43
Q

Working depth

A

This equals addendum plus the dedendum minus the clearance 

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44
Q

Whole depth

A

The height of the whole tooth, which includes addendum plus the dedendum

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45
Q

Circular pitch, or gear pitch

A

Centre of tooth to centre of next at the pitch circle

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46
Q

Pitch circle

A

Approx the middle of the theeth

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47
Q

Pressure angle

A

Angle between line of action. 20-14 1/2 most common

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48
Q

Diametral pitch

A

Number of teeth divided by pitch

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49
Q

Gear ratios

A

Driven divided by drive

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50
Q

Shaft position

A

Parallel
Intersecting
Crossings over

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51
Q

Mitre gears

A

Are bevel gears intersect at 90

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52
Q

Zerol bevel

A

Has no axial thrust

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53
Q

Hypoid

A

Bevel gear. crossover Larger pinnon. Thrust in either direction

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54
Q

Hypoid

A

Needs ep oil. Straddle mounted

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55
Q

Planetary gear

A

Sun
Carrier
Ring

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56
Q

Backlash

A

Is the clearance between gear teeth at pitch line

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57
Q

Tensile members

A

Consist of cords that carry the load

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58
Q

What are the parts to a belt?

A

Top is the cover, load, carrying section are the tensile members, middle, bottom is the compression section.

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59
Q

Pitch line

A

Pitch line runs through the load carrying zone of the belt where the tensile members are located

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60
Q

Which belt has an uncovered sidewall

A

Cogged RAW edge

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61
Q

How is a Cogged RAW edge designated?

A

AX, Bx and CX they are precision, ground for better fit, and grip

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62
Q

Banded belts, they are also called joined classical belts

A

The B C D cross-sections are readily available alignment is critical, because these belts have less ability to flex sideways than individual belts

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63
Q

Banded belts

A

 They were developed to solve problems of belt vibration, whip, and turnover

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64
Q

Fractional horsepower belts

A

2L, 3L,4L and 5L

Generally used on drives less than 1 hp but some manufacturers offer them with ratings up to 17 hp

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65
Q

Open ended

A

They are in a, B, C, D or E with VO at the end

66
Q

Limitations of open ended belts

A

They can only carry 1/3 of a load of a corresponding endless belt

67
Q

Miter gear

A

1~1 intersections at 90

68
Q

Hypoid

A

Shaft is off centre. Large contact area

69
Q

Speed increaser

A

Large gears drives small gear

70
Q

Internal gears have

A

More tooth contact

71
Q

As the angle of the heilix increases

A

Sliding friction and thrust increases

72
Q

Ratio

A

Driving divided by driven

73
Q

How not to check the mesh pattern on worm wheels

A

Do not use Layout blueing

74
Q

Where would you put the blue?

A

Drive end the shaft

75
Q

What happens if you use too much bluing

A

Poorly formed mesh patterns on the meeting teeth

76
Q

What is mesh pattern?

A

The contact area between two meeting teeth of two gears as one transfers power to the other

77
Q

What is the side of the driven tooth called?

A

Active or drive side flank

78
Q

Backlash

A

 Backlashes the rotational arc of clearance between a pair of mounted gears

79
Q

Backlash can?

A

Cause noise, overloading, overheating of gears and bearings, and even seizure and failure.

80
Q

Why is backlash necessary?

A

To prevent damage by tooth interference

81
Q

When is the minimum backlash required?

A

For applications, involving frequent, starting, and stopping/reversed, rotation, or a load

82
Q

Where is backlash measured?

A

At the pitch circle

83
Q

How can you check backlash?

A

Using a dial, using lead wire, using a feeler gauges manually fitted between mating gears

84
Q

What is held stationary when checking backlash?

A

The worm/shaft

85
Q

External backlash check

A

To be done with lines at the same radius

86
Q

Tire rods or torque arms

A

Are to prevent rotation of the gearbox, and must be mounted in the position that allows the gearbox oil levels to be checked 

87
Q

Where to install a tie rod or torque arm

A

90° angles between output in point of torque arm attachment

88
Q

For larger units such as conveyor drives

A

A spring mountain torque arm would be used, this arm takes up, torsional shock.

89
Q

What is necessary with lubrication?

A

Oil dams, or oil circulation paths, they are to reduce wear on bearings and gears.

90
Q

What are scrapers for?

A

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.

91
Q

What happens to copper tube and fittings?

A

They get work hardened from vibration and pressure pulstations

92
Q

Couple ways you can check oil levels

A

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.

93
Q

Roller chain properties

A

Consists of two basic types of links, which are pin links, and roller links

94
Q

What is a connecting link?

A

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.

95
Q

How do you assemble an offset link?

A

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.

96
Q

Which chain is general purpose?

A

Standard single strand, roller chain

97
Q

Silent chain or timing chain

A

Consists of links, made up of tooth plates

98
Q

Silent chains are used for

A

Transmitting high horsepower in a small space. High speed drives and precision timing.

99
Q

Where would you find a hunting link?

A

On a silent chain, it is used when an odd number of pitches is required.

100
Q

How to join a silent chain

A

A joining pin, or connecting link is used to change the length by two pitches.

101
Q

What are the three silent chain designs

A

Side guides, centre guide, and duplex

Duplex is for serpentine drives 

102
Q

Silent chain parts

A

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

103
Q

What happens if you have too much chain tension?

A

Reduce life, chain and sprocket

Overloading of bearings and driver and driven units. 

104
Q

What happens with to little tension?

A

Chain whip and vibration

Chain can wrap up on one of the sprockets

105
Q

Chain tension for medium speed drives

A

4 to 6%

106
Q

Chain tension for high speed and vertical drives

A

2 to 3%

107
Q

How can chains be tensioned?

A

Adjustable centers, or tightening idlers

108
Q

Chain lubrication methods

A

Manual or drip, bath, and forced

109
Q

Where to apply the oil on a multiple strand chain

A

On the inside of the lower span, this forces oil into the chain by centrifugal force

110
Q

Manual or drip feed lubrication

A

It is intended for low speeds under 600 ft./min.

111
Q

When do you discard a chain?

A

If it is elongated by 3% or more

112
Q

What are the two ways to check elongation

A

Measure it when it’s totally stretched, or lay it beside a new chain, and note the difference in length

113
Q

What should you do if a chain has been subjected to excessive load for any reason

A

You should replace the chain

114
Q

What does the wrap angle depend on with sprockets?

A

The wrap angle on a small sprocket is smaller when the ratio is larger

Centre distance between sprockets

115
Q

What must a wrap angle be?

A

120°

However, an angle can go as low as 90° if proper chain tension is closely monitored

116
Q

Inspection of chains and sprockets

A

If an unusual noise occurs, ensure the chain is getting enough lubrication. You might have to apply lubricant manually

117
Q

Open ended belt construction

A

Strong envelope for a good fastener retention

multiple ply square woven fabric tension members provide reinforcement for cushion

Tear resistant breaker fabric

118
Q

Where would you find an open ended belt

A

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

119
Q

Limitation of open ended belts

A

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

120
Q

Installation of V belts

A

Needs to be installed correctly to attain maximum belt life

121
Q

What can happen if dirt or deposits get on the belt or sheave

A

They degrade the belts and sheaves through abrasion and corrosion

They also produce an imbalance in rotating sheaves

122
Q

What is the main reason for cleanup
Of sheaves

A

To inspect for possible cracks, especially around the hub and to ensure dynamic balance.

123
Q

Where should you not use an idler pulley?

A

On reversing devices

124
Q

What does an outside idler pulley do?

A

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

125
Q

What do inside idlers do?

A

Decrease the ark of contact

126
Q

What should you use for an inside idler?

A

If possible, use a groove, pulley, as it provides better tracking

127
Q

Where to place an inside idler

A

As far from the pulley that the belt travels towards in order to prevent unequal arc of contact.

128
Q

Where would you find belt whip?

A

Long spans.

129
Q

Where do you place a contact idler

A

1/3 of the span distance from the larger pulley on the slack span

130
Q

Outside idler goes to the left of the slack side. Driven side.

Inside idler goes to the right of the slack side Driver side

A
131
Q

Synchronous belts are also called

A

Positive drive belt or timing belts

132
Q

What were timing belt used for?

A

For drives that could not tolerate any slippage. Alignment needs to be tits.

133
Q

What is a pitch of a timing belt or anything for that matter

A

The distance from one tooth on the belt to a corresponding point on the next tooth

134
Q

What is a disadvantage of synchronous belt drives

A

Standard neoprene belts do not meet the static conductivity requirements for operation in explosive environments.

135
Q

Synchronous belt, drive efficiency

A

98%

136
Q

What is a pulley

A

A pulley is a wheel used to transmit power from its rim to a belt

137
Q

What is a sheave?

A

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

138
Q

What is a sprocket?

A

It is a pully with grooves running across the rim

139
Q

Types of sprockets

A

Flanged, sprocket and unflagged sprocket

And an eagle sprocket, they have their own coding system

140
Q

Gearbox types

A

Open gear drives, enclosed gear drives,

141
Q

What are open gear drives good for?

A

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

142
Q

Enclosed gear drives

A

When everything is enclosed to protect from outside elements, such as dirt, water, and particles. They can have either oil or grease lubrication.

143
Q

What is the addendum?

A

Radial distance from the pitch circle to top of the land of the tooth

144
Q

Dedendam

A

The radial distance from the pitch circle to the bottom end of the tooth

145
Q

Narrow belt drives

A

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

146
Q

Wet disk drives

A

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.

147
Q

Variable fill, or scoop tube

A

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.

148
Q

Torque converter location

A

Torque converter type units are usually bolted directly onto the internal combustion engine flywheel’s

149
Q

Parts to the torque converter

A

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 

150
Q

Torque converter operation

A

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

151
Q

What is a gear train with three or more shaft called

A

A compound

152
Q

Which side of the gear is always in contact

A

Drive side

153
Q

Type of tooth profile that is not straight cut

A

Involute

154
Q

Gearing, system requiring one gear to be floating on the shaft

A

Herringbone

155
Q

The angle between the lines of contact on a gear system

A

Pressure

156
Q

The device that controls the power transmission in a fluid clutch

A

Scooptube

157
Q

Two types of clutchS that slip during engagement

A

Fluid and friction

158
Q

Type of positive clutch that is one directional

A

Spiral JaW

159
Q

Types of gearboxes

A

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.

160
Q

What is more efficient? belts or chains

A

Chains

Millwright 2 (4 decks)

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