Exam (elaborations)
Millwright Level 2 – Bearings – Questions & Answers
- Course
- MILLWRIGHT
- Institution
- MILLWRIGHT
Millwright Level 2 – Bearings – Questions & Answers
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Millwright Level 2 – Bearings – Questions & AnswersWhat are the principle parts of a friction bearing housing? ✔️Ans -
Base, Base bolt slots, cap and cap bolt holes.
What are friction bearing housings made from adn what factors influence
the choice of housing? ✔️Ans - 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? ✔️Ans - In a fraction of
their nominal size.
Do all new bearings of the same shaft size have the same base-to-eye
measurement? ✔️Ans - If they are from the same manufacturer.
What factors influence the choice of bearings? ✔️Ans - 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 ✔️Ans - 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? ✔️Ans -
Position of the top half may affect the bearing tolerances and load
positions.
What qualities should a good bearing material have? (5 points) ✔️Ans -
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) ✔️Ans - 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? ✔️Ans - Heat, , water saturation.
What is the hardest and toughest babbitt made from? ✔️Ans - Tin
(90%)
How does overheating affect babitt? ✔️Ans - Service life is greatly
reduced
How is babbitt held in bearing casting? ✔️Ans - Holes or slots.
Describe the procedure for pouring a babbitt bearing using a mandrel. (6
Steps) ✔️Ans - 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
5. Hold the babbitt with the pair of pliers
6. Melt it into the bearing with the torch.
What must be checked when fitting a bearing? (4 points) ✔️Ans -
surface finish area of contact, running clearance, lubrication entry, and
grooves
Describe the purpose of tinning. ✔️Ans - To secure a thin skin of babbitt
to a metallic backing.
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