Hydraulic Elevators

What you'll learn

• Describe the main types of hydraulic elevator, in-ground, holeless, telescopic and roped, their parts, uses, strengths and weaknesses, and the code and regulator that govern them
• Calculate jack pressure from load and plunger area, pump flow from car speed, hydraulic and motor power, and pipe velocity and friction losses, and use gauge readings, car speed and motor current to judge a system
• Explain how temperature, viscosity and contamination by water, air and particles affect hydraulic oil and the ride, and estimate the heat generated by elevator traffic and the need for cooling
• Identify the parts of a power unit, explain how positive-displacement pumps and pump motors work, check pump flow by timed runs, check tank volume and oil level, and explain low oil protection
• Explain how mechanical and electronic control valves shape the up and down runs, calculate slowdown distance and stopping error, and follow a manufacturer's valve adjustment procedure
• Describe the construction of jacks, cylinders, plungers and packing, explain why buried cylinders fail and how protected installations prevent it, and explain plunger buckling
• Explain holeless, synchronized telescopic and 2:1 roped hydraulic arrangements, calculate their pressures, strokes and flows, and list the additional devices and checks each requires
• Follow the controller's sequence for up and down runs, compare across-the-line, wye-delta and soft starters, and explain phase protection, re-levelling, battery lowering and fire service operation
• Explain how relief valves, check valves, shut-off valves, rupture valves, overspeed valves and plunger grippers protect a hydraulic car, and check a rupture valve setting against normal down flow
• Measure drift and leakage, separate internal from external leaks with the shut-off valve, and carry out the relief valve, hose and fitting, and anti-creep tests safely and within code limits
• Plan and carry out hydraulic maintenance under a maintenance control program, find and repair leaks, keep an oil log, and prevent, contain and report oil spills
• Acceptance test a new hydraulic installation and troubleshoot a hydraulic elevator methodically, from making it safe through measurement and repair to proof by test and a written service record