MILLWRIGHT LEVEL 2 FINAL EXAM 2024-2025, Exams of Nursing

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MILLWRIGHT LEVEL 2 FINAL EXAM

2024-2025 WITH ACTUAL CORRECT

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What are the principle parts of a friction bearing housing? Base, Base bolt slots, cap and cap bolt holes. What are friction bearing housings made from adn what factors influence the choice of housing? Cast Iron, Cast Steel, Fabricated Steel. Choice depends on the Load, The Rotational Speed, the Direction of Pull and the Support Design How are friction bearing dimensions expressed? In a fraction of their nominal size. Do all new bearings of the same shaft size have the same base-to-eye measurement? If they are from the same manufacturer. What factors influence the choice of bearings? Load, Rotational Speed, Direction of the Pull and support Design What are the applications for the following bearings? a)Solid Bearings b)Split bearings

c)Angle bearings d)Integrated Bearings a) Where Speed and Load are low. Where load is applied on the top part of the bearing. b) Where load is applied on the bottom portion of the bearing. Different bolt numbers for loads. c)When load is applied parallel to, or at a slight angle to, the horizontal. Or when the bearing is mounted on the vertical support d)Where the bearings are an integral part of the machine. How does friction bearing joint design affect its integrity? Position of the top half may affect the bearing tolerances and load positions. What qualities should a good bearing material have? (5 points) Softer than the shaft material, low coefficient of friction, wear-resistant, a good heat conductor and remain relatively stable with heat changes, readily available. List Metals generally used in bearing liners and their applications. (5 points) Babbitt - for general use Brass (copper zinc alloy) - for higher speeds and heavier load than babbit Bronze (coper tin alloy) - for higher speeds and heavier loading than babbitt Aluminum - hydraulic pumps Sintered Bronze - Porous bronze with a built in oil supply. 2:1 ratio. What characteristics of nylon polyurethanes and phenol laminates affect their applications? Heat, , water saturation. What is the hardest and toughest babbitt made from? Tin (90%) How does overheating affect babitt? Service life is greatly reduced How is babbitt held in bearing casting? Holes or slots. Describe the procedure for pouring a babbitt bearing using a mandrel. (6 Steps)

1. Gather Equipment ( oxyacetylene torch putt pliers, babbitt)
2. Fit the torch with a large tip and melt out the remaining babbitt in the casting 3.Smoke the shaft with a straight acetylene flame. 4.Put a putty dam around the shaft and bearing
3. Hold the babbitt with the pair of pliers
4. Melt it into the bearing with the torch. What must be checked when fitting a bearing? (4 points)

surface finish area of contact, running clearance, lubrication entry, and grooves Describe the purpose of tinning. To secure a thin skin of babbitt to a metallic backing. Describe the tools used to fit a friction bearing. Scraper, files, groove chisels. Describe procedure for fitting a bearing.

1. Chamfer the top edges or cut an oil groove
2. check bearing for contact by coating mandrel in bluing and rotating mandrel
3. Shave down high spots indicated by bluing Describe the procedure fro shimming a bearing to the correct amount of clearance. Insert shims, make sure they do not make contact with the shaft or the chamfer. Tighten bolts to specs and rotate the shaft. Add shims or realign the cap. Describe the procedure for checking bearing clearance with a dial indicator, Pastigage and lead wire. ( points)
4. Place indicator on both ends of the shaft and adjust to acquire an even reading.
5. Insert plastigage and tight cap to proper torque and measure width to determine clearance. 3.Same way as plastigage Described how preformed bearings are installed and held in place. Press preformed bearing into housing with the cap. Or press fit Describe procedure for installing bushings. Pressure fit or crushed into housing Describe how thrust is controlled with plain bearings for both low and high speed applications. Oil wedges. Describe radial and axial load. Radial is horizontal load, axial is vertical. Describe the basic design of Kingsbury bearings. Faces have a minor pivoted shoes and oil is injected to so during operation the shaft is centered in clearance accurately. What styles do kingsbury bearings come in? (2 points) Fixed pad and floating or tilting pads. What are the merits of anit-friction bearings?

A lot less friction occurring. Less energy, less heat. List the main parts of anti-friction bearings? (3 points) 2 hardened steel rings, the hardened balls or rollers (rolling elements) and the separator. Describe the operating principle of ball bushings. Guide rails/shafts using recirculating ball bushings. List the three styles of rolling elements. Ball, Roller and needles Describe the applications for open bearings, shielded bearings, sealed bearings and sealed and shielded bearings. Open bearings - oil bath or open lubrication Shielded bearings- keep out solid contaminates Sealed - Keeps out solid contaminates and liquid contaminants. How are directions of bearing loads expressed? Radial and thrust and combination What are the normal speed ranges for ball bearings and roller bearings? Ball - 40,000 rpm Rolling - 2000-20,000 rpm How are bearings classified according to their service use? Type, Service Weight, Bore size. (X, X, XX) What measurements are matched to the code markings on a bearing? Last two numbers correspond with bore diameter. (00-10mm, 01-12mm, 02-15mm, 03-17mm) Above 20mm multiply last two digits by 5. Above 480mm, size is directly placed in Briefly describe: a) non-separable bearings b)separable bearings c)non-aligning bearings d)self aligning bearings a)Non-sperable - designed in single peice b)Separable- Can pull bearing, consist of either 2 or 3 separable parts c)non-aligning - used in machines where the bearings are held in alignment by the bores of the housing d)self-aligning - may be internal or external. outer race is more concave to allow for pivot. Define the following bearing codes: a) SKF

b) SKF- c)FAG-6108K a)skf=manufacturer 06=rolling element 6=service weight 06=30mm b)skf=manufacturer 22=rolling element 3=service weight 10=50mm c)FAG=manufacturer 6=rolling element 1=service weight 8=40mm k=taper Why is there a need for bearing clearance? (3 Points) It compensates for expansion of inner ring or contraction of outer ring. It compensates for differential expansion of the two rings when internal operates at a higher temp than the outer. It affects the end play of ball journal bearings and their capacity for carrying axial loads. the greater the clearance the greater the load. Define: a) Initial Clearance b)installed clearance c)running clearance a) uninstalled clearance; as it comes out of the box b) clearance left on the bearing after installation and fixed c) clearance when machine is operating at temperature and lubrication is supplied Which bearing has the most clearance, a standard bearing or C4? c Which bearing is more accurately manufactured? c What checks should be made before fitting a bearing? diameter, roundness, shaft deflection, surface damage, general finish, any damage to the shoulder supporting the inner ring, cracks in the housing Define the following: a)push fit b)pressure fit c)interference fit a) bearing is installed by hand without mechanical aid b) use a tube to distribute the force evenly. Always apply pressure on part that is being secure. (ie place pressure on inner ring if pressure is on the shaft) c)description on how tightly the bearing fits around the shaft. How does and interference fit affect the bearing clearance? it will decrease the clearance.

Which bearing ring has the press fit on a straight bore bearing? Inner Race Describe the procedure for pressing a bearing onto a shaft and pressing a shaft through a bearing.

1. Apply a coating of oil 2.Put the bearing on the shaft, makes sure its perpendicular 3.Place a clean pipe or mounting tube slightly larger than the shaft diameter on the inner ring of the bearing 4.apply pressure by hand to start the bearing moving 5.Check the position of the bearing to see that it is still squarely on. 6.Press it on final position 7.As bearing moves down the shaft rotate the outer ring by hand to check for drag or loss of clearance. Describe the procedure for chilling to shrink fit a bearing. Shrink the bearing with dry ice/ alchohol or compressed air. What is the maximum temperature that a bearing should be heated to for expansion purposes? 120 degrees celcius Briefly describe: a)Heat lamps b)oven c)induction heater d)oil bath a) Heat bearing. Used on small bearings b) Can heat up bearing saftely becuase of temperature control c) Uses electricity to heat up bearing, no way of determining heat. use heat crayon d) Bathe large bearings in a heated oil. make sure bearing doesnt touch bottom of the pot. Describe the procedures for installing a hot bearing on a shaft and installing the bearing outer ring in a housing. Place bearing on shaft as quick as possible and hold. if resistance is felt, remove and reheat. Describe the methods used to positively position the inner ring and the outer ring in its axial position. inner ring - snap ring in a groove cut in the shaft or housing; large washer witha lock nut. outer ring - End caps for positive position w/ or w/out shims; snap ring is in the housing Define fixed bearing and floating bearing. * fixed bearings do not allow for axial variance. floating do What is the reason for having one fixed and one floating bearing on most shafts? to allow a minimal amount of axial clearance and stop the journal

Describe how axial clearance is adjusted using shims. shims can be applied either by the end cover and the bearing cup OR between the end cover and machine housing Describe the applications for the following angular-contact bearing arrangements: a) back-to-back b)face-to-face c)tandem a)back to back - What is the purpose of using tapered-bore bearings with tapered sleeve adapters? Briefly describe how the taper sleeve adapter positively positions the bearing. Describe the procedure for installing or mounting the following bearings: a)ball bearing, using tapered sleeve adapter b)tapered-bore bearing, using hydraulic unit c)spherical roller bearing, used tapered sleeve adapter What is the rule of thumb for setting the standard-clearance on a spherical roller bearing if there are no tables available? Describe the non-destructive removal of bearings using the following methods: a)press b)bearing splitter and puller c)cup or inside puller Compare withdrawal sleeves to adapter sleeves. What is the maximum temperature that a bearing should be heated to for expansion purposes? 120 degrees celcius Briefly describe: a)Heat lamps b)oven c)induction heater d)oil bath a) Heat bearing. Used on small bearings b) Can heat up bearing saftely becuase of temperature control c) Uses electricity to heat up bearing, no way of determining heat. use heat crayon d) Bathe large bearings in a heated oil. make sure bearing doesnt touch bottom of the pot. Describe the procedures for installing a hot bearing on a shaft and installing the bearing outer ring in a housing. Place bearing on shaft as quick as possible and hold. if resistance is felt, remove and reheat.

Describe the methods used to positively position the inner ring and the outer ring in its axial position. inner ring - snap ring in a groove cut in the shaft or housing; large washer witha lock nut. outer ring - End caps for positive position w/ or w/out shims; snap ring is in the housing Define fixed bearing and floating bearing. * fixed bearings do not allow for axial variance. floating do What is the reason for having one fixed and one floating bearing on most shafts? to allow a minimal amount of axial clearance and stop the journal Describe how axial clearance is adjusted using shims. shims can be applied either by the end cover and the bearing cup OR between the end cover and machine housing Describe the applications for the following angular-contact bearing arrangements: a) back-to-back b)face-to-face c)tandem a)back to back -outer ring , push fit b)face to face - inner ring , push fit c)tandem-both rings , press fit What is the purpose of using tapered-bore bearings with tapered sleeve adapters? A tapered adapter sleeve allows you to install , a bearing any where on the shaft. Briefly describe how the taper sleeve adapter positively positions the bearing. The outer face of the sleeve is tapered to match the tapered bore of the bearings inner ring. Describe the procedure for installing or mounting the following bearings: a)ball bearing, using tapered sleeve adapter b)tapered-bore bearing, using hydraulic unit c)spherical roller bearing, used tapered sleeve adapter A) ball bearing - rotate the outer race and swivel it slowly while tightening the locknut. There will be a light drag , when the clearance is reduced. Stop tightening and lock the nut in position with the tab washer.

B) What is the rule of thumb for setting the standard-clearance on a spherical roller bearing if there are no tables available? A rule of thumb is to reduce the initial clearance by roughly 50%.

Another rule of thumb is to convert the last two figures of the bearing number into thousandths of an inch. Describe the non-destructive removal of bearings using the following methods: a)press b)bearing splitter and puller c)cup or inside puller A) press-All strain is applied to the inner race and the strain is even on the opposite side.

B) bearing splitter and puller-Pull on the outer ring , wrap the outer ring incase it breaks.

C)cup or inside puller-jaws have to be inserted behind the shoulder. Compare withdrawal sleeves to adapter sleeves. Withdrawal sleeve- solid bore housing , shaft is machined as needed , sleeve slides under the bearing , driving nut is threaded onto the shaft, bearing is held by a shaft shoulder or a machined part against the inner ring , the bearing first , and then the sleeve.

adapter sleeve-split bored housing , no shaft changes , bearing slides over the sleeve , driving nut is threaded onto the sleeve , bearing does not need a backing or shoulder , the bearing first , and then the sleeve. Describe the non-destructive removal of bearings which are mounted on adapater and withdrawal sleeves. Describe the destructive removal of bearings and cups. Describe the process and procedure for removing bearings with oil injection. uses the force developed by oil or grease under pressure to expand the inner ring of the bearing. Describe the construction of horizontally split, vertically split and one piece pillow block bearing housing. Describe the installation and removal of pillow block bearings. Describe the installation or mounting of flange bearings, needle bearings and thrust bearings. To what level should you fill a grease lubricated, pillow block bearing? and roller bearings in oil? 1/3rd to 1/2" in a pillow block , 1/3rd to 1/2" up the roller. how much is running clearance? Half a thou. what safety precaution must be taken when removing any bearing from a tapered seat? Have a locking nut threaded on the end of the sleeve to catch the bearing.

what type of bearing load puts most of the load pressure on the bottom 2-3 elements and side pressure on all elements in the bearing? a combination load. which of the following bearing bearings can accept slight misalignment between the shaft and housing under high loads? Double roll spherical bearing. What bearing has rubber , and bronze? A cutless bearing. What is the purpose of a adapter sleeve? To adapt a bearing anywhere on the shaft. What is the melting range of babbit? 275-285degrees celcius. How much contact area is required on a babbit bearing? 75% to 85% What is the term given to the contact areas for a roller and ball bearing? roller for Line contact , and ball point contact. What should coat the shaft of the mandrel when pouring a babbit bearing? Carbon. What is the rule of thumb for a plain bearing clearance? 0.001 " per inch. How many rollers are loaded in a tapered roller bearing? All rollers. What is the name of a common babbitt style thrust bearing? A kingsbury bearing. What type of roller bearing cannot accept any thrust loading? A Cylindrical bearing. What is the term used to know the amount of thrust loading? Material interference. what are the following bearing codes? A) RS

B) Z

C) W

D) K

E) C

F) P

A) rubbing b) shield c) oil groove d) taper E) internal clearance F) Progressive What changes if a bearing service weight is increased? The outer diameter. What is the difference between a withdrawal sleeve , and A adapter sleeve? A adapter sleeve can be mounted anywhere on the shaft (threads Near the taper ) A withdrawal sleeve is installed at the end of the shaft. ( threads by the wider part of the sleeve) What do you look for in a pillow block mounted bearing to see if it is fixed or floating? stabilizing rings , close to the drive. What should be worn when greasing a bearing? Latex gloves. What happened's to the shaft when you shim a bearing? The shaft will move towards the shims. What types of bearings are used to control linear motion? Guide bearings , and pivoted shoe bearings. How do you tell if a bearing is failing? temperature rise , increased vibration , unusual noise. What kinda bearing is used when installation and removal of bearings is not practical? A cooper bearing may be used. How do you prevent a bearing from contamination? By keeping the surrounding things clean.

what kinda load does a thrust bearing carry? Thrust (axial) loads , Because of centrifugal force , and limited speed. What are the parts for a dual direction thrust bearing? two housing washers , and one shaft washer. How do you mount thrust bearings? Fit one ring to the housing , and the other to the shaft. What are two ways a inner ring is held in place? -Threaded two setscrews into a collar. -Self locking collar ( camlock) How is a pillow block mounted? , and what should you do to a shaft for easy removal? -Parallel to the shaft. -file a flatspot on the shaft. How much psi does a grease gun develop? over a 1000psi. What are the three temperatures for pouring babbitt? -Complete melting point-275 to 285 degrees Celsius -pour point 343 to 371 degrees celsius -complete solidification point-25 to 28 degrees celsius

Describe the non-destructive removal of bearings which are mounted on adapater and withdrawal sleeves. Describe the destructive removal of bearings and cups. Describe the process and procedure for removing bearings with oil injection. Describe the construction of horizontally split, vertically split and one piece pillow block bearing housing. Describe the installation and removal of pillow block bearings. Describe the installation or mounting of flange bearings, needle bearings and thrust bearings.