What is the difference between a vertical platform lift a cargo lift and an elevator?
Vertical platform lifts or vpl's are wheelchair lifts. They are limited to 14' of upwards travel. Cargo lifts are material or freight lifts. Cargo lifts are not passenger compliant according to ASME 17.1 or 18.1. An elevator is a broad term for any vertically moving device that carries a load. Passenger elevators are built to a stricter set of guidelines than vpl's and thus are not limited to 14' of travel.
What does it mean if an elevator is ADA compliant?
The Americans with Disabilities Act is mostly concerned with accessibility. There is a number of things ADA states about elevators. One example is the platform size needs to be large enough for a wheelchair, and an individual behind them pushing the wheelchair. ADA does not speak to safety concerns relating to machine failure. Being ADA compliant might be required by law if you are in a commercial or government building. It is never required in your own home. Whether or not ADA compliance should be important to you depends on your situation.
What is ASME 17.1 and ASME 18.1?
ASME is the American Society of Mechanical Engineers. They are not a government agency but many government agencies look to them for guidance relating to product safety. The guidelines ASME has written for VPL's is ASME 18.1. ASME 17.1 is the guidelines written for elevators. All vertically moving platforms that rise 14 feet or more should be built to ASME 17.1.
What are type A safeties?
Elevator brakes that automatically engage in the event of a failure are referred to as "safeties." If an elevator advertises type A safeties it means the brakes engage instantly, or close to instantly, and bring the elevator to a quick stop. Elevators that serve tall buildings and move at high speed may employ type B or C safeties that come to a more gradual stop. ASME 17.1 AND 18.1 state all elevator safeties must clamp the member they engage between 2 surfaces. Elevator safeties that push against one side of any surface are not compliant.
What's the difference between winding drum, traction, screw drive, chain drive, direct plunger hydraulic, and roped hydraulic?
The winding drum is what we use on both our passenger and cargo lifts. "Drum" is another term for the spool. A winding drum elevator has a rotating spool that winds the cable onto it like a fishing reel. Winding drum elevators are limited by how high they can go because the spool has to be big enough to wrap enough cable to get the elevator car to its top landing. Our winding drum "winch" is limited to roughly 40 feet of cable.
Traction elevators move by rotating a pulley, or several pulleys. The cable (or cables) that are in the pulleys are attached at one end to the elevator car, and to a counterweight at the other. These systems rely on the friction between the cable and pulley and to move the load. Traction elevators are common in buildings too tall for a winding drum elevator. They are not well suited for outdoor installations because debris and contamination tend to collect on the cable and pulley and disrupt the friction.
Chain drive usually functions as a traction elevator but rather than relying on friction between a cable and pulley a roller chain and sprocket is used, much like you would see on a bicycle. Contamination issues that disrupt the friction may not be an issue. Contamination, particularly sand and salt may lead to premature wear in outdoor installations, however.
Screw drives raise and lower the load by turning a screw. The elevator car has essentially attached the nut. They are subject to contamination issues in outdoor installations. Screw drive lifts require frequent lubrication which tends to attract sand and grit. Screw drives are impractical for lifts moving more than 1 story because the length of the screw has to be at least as long as the travel of the elevator car. They are typically just used on vpl's.
Direct plunger hydraulics move via fluid being pumped into an actuator which pushes the lift car upwards. Usually, the actuator is in the ground with these types of systems. Hydraulic systems are subject to oil contamination if installed outdoors, and generally require a machine room to house the hydraulic pump.
Roped hydraulic functions similarly to direct plunger hydraulic, however, the hydraulic actuator pulls cables that lift the car. They are subject to the same issues as a direct plunger, but generally do not require anything underground.