HYDRAULIC ELEVATORS – Background, Specs, Types, Pros & Cons

Hydraulic elevators are one of the most popular multi-level structures in the world. They function to transport people and loads from one floor to another. These elevators have made transportation of equipment and people easier, and have allowed the disabled people to move between upper and lower floors.
    In today’s time, there are three type of elevators that are being used in buildings. These types are: Hydraulic elevators, traction elevators, and Machine Room-Less elevators. The hoisting system used to lift the elevator cabs usually use either wire/rope traction or hydraulic system. The hydraulic system basically works on Pascal’s law of incompressibility of fluid. This law emphasizes that the pressure applied on any point of the fluid gets transmitted throughout without diminishing. Hydraulic system uses this law for power generation and transmission.

      Background of Hydraulic Elevators

      Hydraulic elevators were first manufactured in the 19th century and were used in a few European factories. The elevator cab was fixed on the top a steel plunger. To move the elevator, the plunger dropped into a cylinder which was fitted in the ground. The water was then released into the cylinder with high pressure which resultantly raised the plunger and the cab attached to it. In the oldest models, the flow of water was controlled by a main valve which was operated by the passengers via ropes that ran vertically through the elevator cab. In later models, pilot valves and lever control were added to the elevators for acceleration and deceleration. In late 1870’s, hydraulic elevators with rope-geared system were introduced. In these models, the steel plunger was replaced by a short piston which moved inside the cylinder that was fitted in the building. With this hydraulic system, the length of piston stroke was improved using pulleys and ropes.

        Specifications of Hydraulic Elevators

        • Hydraulic elevators can work efficiently up to 5 or 6 floors.
        • Piston-powered hydraulic elevators a have typical speed of around 150 ft. per minute.
        • There are three main types of hydraulic elevators: roped, in-ground (roped), and hole-less.
        • All hydraulic systems have four main components: a pump powered by electric motor, a tank (where the oil is stored), a cylinder, and a valve between the tank and cylinder.
        • all hydraulic elevators require a pit below the elevator shaft.
        • The weight carrying capacity of these elevators varies with size of the cab and typically ranges from 2000 pounds to 5000 pounds.
          • Pros of Hydraulic Elevators

          • Hydraulic elevators have low installation and maintenance costs
          • Easy and quick installation
          • These elevators do not require an overhead machine room
          • These elevators have minimized hoist-way dimensions.
          • Their machine rooms can be remotely located
          • Hydraulic elevators can transport heavy loads
            • Cons of Hydraulic Elevator

            • Hydraulic elevators have limited performance and speed.
            • The quality of their ride is lower than other types of elevators
            • They require machine room for control components
            • They are only suitable for low and mid-rise buildings
            • Hydraulic elevators require high energy for functioning and are thus energy-inefficient.
              • Types of Hydraulic Elevators

                  In-ground (Holed) Hydraulic Elevators
                    These hydraulic elevators have a cylinder which is extended into the ground to a depth equal to the height of the highest floor where the elevator will be traveling. The bottom of their elevator cab is fitted on a piston which moves inside the cylinder. However, if there are any obstacles underground such as bedrock, high water table, or unstable soil, the cylinder would be very difficult or impossible to install. This can be a major drawback to a holed hydraulic system.
                      Hole-less Hydraulic Elevators
                        In hole-less hydraulic elevators, the cylinder is not extended into the ground. These elevators are used when drilling hole in the ground to extend the cylinder is not possible due to some obstacles. Hole-less hydraulic elevators have above-ground cylinders which are fitted under each side of the elevator cab.
                          Roped Hydraulic Elevators
                            These elevators use a combination of both hydraulic power and ropes to move the elevator cabs. Roped hydraulic elevators, instead of connecting the plunger to the cab directly, couple it to the cab by using rope and pulley arrangement. This rope and pulley system supports the elevator cab and its load. These elevators use a shorter jack and therefore allow for a greater range of cab travel.