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Hydraulic Elevators

We install hydraulic elevators by a variety of manufacturers.

Commercial hydraulic elevators fall into two basic categories; conventional (or in-ground) and holeless.

All hydraulic elevators are driven by a pump and motor combination. The actual lifting is done by a piston mounted within a casing or cylinder (jack assembly). Car speed, acceleration, deceleration and relief pressure are regulated by a control valve mounted between the pump and the cylinder. When the motor turns the pump, the pump creates pressure which drives the piston and elevator up. To come down,  a valve is opened which allows the oil previously pumped into the casing to flow back into the reservoir, allowing the car and piston to come down .

In-ground elevators are so called because the cylinder goes down into the ground as far as the elevator travels up. This type of installation requires the drilling of a hole below the elevator. Typical installations today utilize a PVC liner to protect the steel cylinder from electrolytic action and other chemical reactions. RMR does not install this type of elevator. Due to the inability to observe and maintain the jack assembly after it is placed into the ground, we have determined that there is no need to expose our customer or our firm to the liability associated with an underground hydraulic oil leak.

Holeless elevators are called so because they do not use a conventional piston/casing arrangement. Holeless elevators come in many different styles. The two predominant types are direct-acting and roped. Holeless hydraulic elevator equipment is typically more expensive than in-ground equipment; however, the additional expense is offset by the high cost of drilling a jack hole. Thye other benefit to hole less equipment is that there is no possibility of an environmental contamination.

Direct acting holeless elevators employ a piston that is connected directly to the steel that supports the elevator cab. Typically this requires either a cantilevered platform support or a second jack assembly. Also included in this category are telescopic jacks that have multiple pistons within a single jack assembly. Direct acting hydraulic elevators are only practical for a limited amount of travel.

Roped hydraulic elevators are more complicated as they employ an indirect attachment to the car. Roped hydraulic elevators utilize the same steel cables that support high rise elevators but in a 1:2 arrangement. (See Illustration} In this manner the cab will move two inches for every inch the piston travels. Roped hydraulic elevators are well suited to existing buildings, applications where drilling a hole for the jack assembly is impractical or in an application where travel is more than is practical for a direct acting hydraulic elevator.


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