Traction Elevators, Machines and Ropes

What you'll learn

• Describe the main traction elevator layouts, overhead 1:1, double wrap, 2:1, basement and machine-room-less, their parts and uses, and calculate the hoist power from the unbalance, speed and efficiency
• Apply the capstan equation to the rope tensions on each side of a drive sheave, including the effect of acceleration, and explain how wrap angle and groove shape set the traction a car must have and must not exceed
• Explain 1:1, 2:1 and higher roping, single and double wrap and underslung arrangements, calculate rope speed, sheave speed, wrap angle and D/d ratio, and explain how sheaves, bends and alignment affect rope life
• Calculate counterweight weight and unbalance, carry out and interpret a balance test, correct the balance with filler weights, and size compensation to cancel the swing of hoist rope weight
• Explain how worm-geared traction machines work, calculate gear ratio, efficiency and motor torque, and inspect gear oil, end play, backlash, bearings and couplings against limits and trends
• Describe gearless and permanent-magnet machines, calculate sheave torque and drive frequency, explain encoder alignment, and work safely on a machine whose motor generates voltage whenever it turns
• Explain the layout of machine-room-less elevators, work safely on a hoistway-mounted machine from the car top, and carry out a passenger rescue by emergency power supply or pulsed brake release
• Describe wire rope construction and terminations, calculate the factor of safety against the code minimum for the rope speed, and inspect ropes for diameter, broken wires, rouge and damage against replacement criteria
• Explain coated steel belts, their monitoring and replacement criteria, test a residual strength detection device, handle belts without damage, and describe electromagnetic rope testing
• Explain how spring-applied brakes work and what the codes require of them, including ascending car overspeed and unintended movement protection, calculate brake torque and stopping distance, and adjust and test a brake
• Measure groove wear and rope heights, decide when a sheave must be regrooved, measure and equalize rope tensions, and diagnose traction problems from their symptoms
• Plan and carry out a suspension rope replacement with the car and counterweight secured, set rope length for runby, equalize tensions, prove the work by brake and traction tests, and write the record