Elevator 245-250: Questions With Correct
Solutions
How do you determine the gear ratio? Correct Answer - By
dividing the number of threads on the gear by the number of teeth
on the ring gear
What is the main benefit of using the V groove? Correct Answer -
Prevents rope from slipping out of the groove
What is the max speed used with V grooves? Correct Answer -
500fpm
What type of grove is cut into the drive sheave to increase the
traction between the machine sheave and rope without double
wrapping? Correct Answer - V groove
What should the oil level inside the worm gear case be maintained
at? Correct Answer - The center of the case
What are the two types of machines used to operate elevators?
Correct Answer - Geared and gearless
What is an advantage of using a U groove? Correct Answer - it
doesn't pinch the rope instead it offers the greatest possible rope
surface which in turn increases rope life.
What are the parameters for a U groove? Correct Answer - The
radius of U grooves on the sheave is slightly larger than the ropes
What are some disadvantages of using V grooves? Correct Answer
- Increased rope stress, possible rope distortion
, What are 2 distinguishing features of a geared elevator machine?
Correct Answer - An enclosed ring gear and the worm gear
What is the maximum speed for a geared machine? Correct
Answer - 500FPM
What is the purpose of the gear reduction unit? Correct Answer -
To increase the lifting capacity of a small motor
What is a major disadvantage of a gearless machine? Correct
Answer - Require a larger brake are to hold the load due to a lack
of reduction gear.
According to code what must the drive sheave be in relation to the
belts or ropes being used? Correct Answer - At least 40 times
the thickness of whatever is being used
Why are gearless machines used in high rise building? Correct
Answer - Easy to maintain, dependable smooth ride, and
perform well in high operating conditions
According to code how much lower, stop, and hold power should
every elevator have? Correct Answer - 125% of the rated
safety load
What is the advantage of installing sheaves overhead? Correct
Answer - It allows for floors to be added to the building
When are sheaves installed overhead? Correct Answer - When
the machine is in the bottom of the hoist way or in an adjacent hoist
way
Solutions
How do you determine the gear ratio? Correct Answer - By
dividing the number of threads on the gear by the number of teeth
on the ring gear
What is the main benefit of using the V groove? Correct Answer -
Prevents rope from slipping out of the groove
What is the max speed used with V grooves? Correct Answer -
500fpm
What type of grove is cut into the drive sheave to increase the
traction between the machine sheave and rope without double
wrapping? Correct Answer - V groove
What should the oil level inside the worm gear case be maintained
at? Correct Answer - The center of the case
What are the two types of machines used to operate elevators?
Correct Answer - Geared and gearless
What is an advantage of using a U groove? Correct Answer - it
doesn't pinch the rope instead it offers the greatest possible rope
surface which in turn increases rope life.
What are the parameters for a U groove? Correct Answer - The
radius of U grooves on the sheave is slightly larger than the ropes
What are some disadvantages of using V grooves? Correct Answer
- Increased rope stress, possible rope distortion
, What are 2 distinguishing features of a geared elevator machine?
Correct Answer - An enclosed ring gear and the worm gear
What is the maximum speed for a geared machine? Correct
Answer - 500FPM
What is the purpose of the gear reduction unit? Correct Answer -
To increase the lifting capacity of a small motor
What is a major disadvantage of a gearless machine? Correct
Answer - Require a larger brake are to hold the load due to a lack
of reduction gear.
According to code what must the drive sheave be in relation to the
belts or ropes being used? Correct Answer - At least 40 times
the thickness of whatever is being used
Why are gearless machines used in high rise building? Correct
Answer - Easy to maintain, dependable smooth ride, and
perform well in high operating conditions
According to code how much lower, stop, and hold power should
every elevator have? Correct Answer - 125% of the rated
safety load
What is the advantage of installing sheaves overhead? Correct
Answer - It allows for floors to be added to the building
When are sheaves installed overhead? Correct Answer - When
the machine is in the bottom of the hoist way or in an adjacent hoist
way
