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Welcome to Classroom on demand, your source for educational materials related to the vertical transportation industry. This site represents the knowledge and expertise of the best engineers and mechanics in the elevator industry, and will help those new to the elevator industry learn about the basic workings of elevator systems, and also will serve as a reference for people with more experience.

Car Sling - Gearless

Isolated Platform
The platform serves as the base on which you mount the cab. It also is the surface on which passengers stand or freight rests on. On passenger cars, the cab door sill is mounted to the platform.
Platforms are fabricated out of structural or formed steel members. A steel or wood sub-floor is attached to the surface of the structural frame. On passenger elevators, the sub-floor receives a finish flooring material after the cab is installed. Most finished floors on the passenger elevators consist of tile or a very short pile carpet with no padding. On freight elevators, the platform's finished floor generally consists of steel checker plate or hardwood flooring.
Isolation Pads: A car platform may be mounted on rubber (or equivalent) pads to reduce noise and vibrations. Platform isolation is usually found on passenger cars with moderate to high speeds (i.e. greater than 200 fpm (1.0 m/s). The isolation reduces noise and vibration transmissions from the sling. This provides a smoother and quieter ride.

The sling is the framework which encloses the cab. The ropes, guides, and platform attach to the sling (also called a car frame). The width of the sling depends on the platform width. The height of the sling depends on the cab height.
A typical sling consists of: two stiles, a safety plank (called a bolster on a hydraulic equipment type), two strike plates, a cross-head, and brace rods.

Sling = stiles, safety plank, cross-head, brace rods, strike plates.
Stiles are two vertical channels, one on each side of the car, running parallel to the rails. The stiles connect to the crosshead and the safety plank. They also provide a mounting point for one end of the brace rods. The length of the stiles is based on the cab height.
Safety Plank
Sling = stiles, safety plank, cross-head, brace rods, strike plates
Safety Plank is the bottom member of a sling for a gearless traction elevator which contains the safety. The stiles connect to the crosshead and the safety plank.

Sling = stiles, safety plank, cross-head, brace rods, strike plates
Cross-Head is the name of channels running horizontally between the stiles at the very top of the sling. The cross-head on gearless traction elevators is the counterpart to the safety planks. In addition, the cross-head is the attachment point for the top rail guides and hoist ropes.
Remember, the cross-head on a hydraulic elevator spaces the stiles apart as a counterpart to the bolsters. The cross-head on a gearless traction equipment type, on the other hand, is the load-bearing structural element of the sling. The load of the car must be considered when sizing cross-heads.
Brace Rods
Sling = stiles, safety plank, cross-head, brace rods, strike plates
Normally, there are four brace rods. One end attaches midway up each stile and the other end attaches to a corner of the platform. Brace rods provide stability and ensure that the platform is level.
Strike Plates
Sling = stiles, safety plank, cross-head, brace rods, strike plates
Two strike plates are attached to the underside of the safety planks. The strike plates are the contact points between the car sling and the buffer springs if the car travels too far below the lowest terminal landing.
Car Hitch Plate
The car hitch plate secures the ropes to the cross-head. Notice that the ropes are secured in the center of the cross-head. This location is unique to traction elevator equipment type.

Safety – Flex Clamp (Type B)
The purpose of the flex clamp safety is to stop and hold the car if the speed is too fast, the ropes have slack in them, or the car is in a free-fall.
The safeties are attached to the safety planks under the car.
There is one type of safety used with the gearless traction elevator: Type B, also known as a flex clamp safety which brings a car to a gradual stop; it can be used on any speed.
Note: If the space below the hoistway is occupied, safeties are also required on the counterweight.

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