Split-Cast Iron Pulleys

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What are the most satisfactory velocities for line shafting and machine belts in factory practice?

1,000 to 3,000 fpm

What are the velocities used for large power transmission with pulley bearings mounted on solid foundations?

5,000 and 6,000 fpm

What are critical speeds in belts indicated by?

Belt riding from side to side on the pulley face and violent flapping of the slack side.

What factors determine the power transmitted by any belt?

Arc of contact, difference in tensions of belts, coefficient of frictions, and center distance. Signup and view all the answers

How can critical speed issues in belts be remedied?

By altering the center distance, the load, or the belt velocity. Signup and view all the answers

What governs the transmitting power in belts?

The pulley with the lower value of friction contact. Signup and view all the answers

What is the advantage of split-cast iron pulleys over solid cast-iron pulleys?

Can be placed between other pulleys on a shaft without removing either the pulleys or the shafts Signup and view all the answers

What is the benefit of wood pulleys over cast iron pulleys in terms of power transmission?

Claimed to transmit 35 to 50% more power for the same belt tension Signup and view all the answers

Why is it recommended to have face widths of 10 inches or over for cast iron pulleys?

Shrinkage strains are greatly reduced or practically eliminated Signup and view all the answers

In what conditions should wood pulleys not be used?

Where they are exposed to excessive moisture Signup and view all the answers

How does the weight of steel pulleys compare to cast-iron pulleys?

45 to 55% less weight for the same power-transmitting capacity Signup and view all the answers

What is the typical percentage of slip difference between steel pulleys and cast-iron pulleys?

2.35 to 2.70 percent less for steel pulleys Signup and view all the answers

What is the recommended maximum speed for steel pulleys?

6000 fpm Signup and view all the answers

What is the recommended maximum speed for wood pulleys with certain construction?

10,000 fpm Signup and view all the answers

What is the minimum pulley face width recommended for belts over 24 inches wide?

3 in. wider Signup and view all the answers

How are standard pulleys crowned?

By making the center diameter 1/9 in. per foot of face width larger than the edge diameter. Signup and view all the answers

What can decrease the power-transmitting capacity of a belt at high velocities?

Centrifugal force Signup and view all the answers

What happens to the power of a belt at higher velocities according to Eq.(16-9)?

It decreases until it is theoretically zero. Signup and view all the answers

What is the formula for power transmitted in terms of torque?

Power = 2πTN Signup and view all the answers

What factors are considered in the method of belt selection according to the American Leather Belting Association?

Service conditions, center distance, pulley size, belt speed, and belt thickness Signup and view all the answers

Why does the power transmitting capacity of the drive decrease in high speed ratio and short center distance drives?

The arc of contact on the smaller pulley decreases Signup and view all the answers

What is the recommended minimum arc of contact in a drive according to practice?

Never less than 155 degrees Signup and view all the answers

What should the arc of contact be in a drive for optimal performance?

Ideally more than 165 degrees Signup and view all the answers

What is the standardized procedure adopted by the American Leather Belting Association for belt selection?

Consideration of service conditions, center distance, pulley size, belt speed, and belt thickness Signup and view all the answers

Why is a fastener required at the joint of a belt?

To prevent the belt from coming apart at the joint. Signup and view all the answers

What happens to the horsepower capacity of a two-ply belt compared to a single-ply belt of the same thickness?

It is reduced to 85 percent. Signup and view all the answers

Why are vertical belt drives less efficient than horizontal drives?

Because the belt does not cling to the lower pulley as well in vertical drives. Signup and view all the answers

What should be done when using crossed belts wider than 8 inches?

Avoid them and use the reversing type of drive with idler pulleys instead. Signup and view all the answers

Why should the power transmitted by an inclined belt be reduced as the degree of inclination increases?

To account for the reduced efficiency of inclined drives. Signup and view all the answers

What does laboratory testing and service experience show about the capacity of a triple-ply belt compared to a single-ply belt of the same thickness?

It is reduced to 75 percent. Signup and view all the answers