How does a hydraulic elevator work

Hydraulic systems of an elevator system

There is a suitable drive system for elevators for every need.

The hydraulic elevator is an alternative type of system to the car counterweight system, which is connected with ropes that are pulled by the drive pulley operated by an electric motor.

The car is connected to a cylinder containing a piston. Mineral oil is introduced under pressure. A valve regulates the flow. When the elevator moves upwards, a pump pushes the hydraulic oil into the telescopic cylinder. This causes the telescopic cylinder to extend and lift the cabin. When the elevator moves downwards, the hydraulic fluid flows back into the hydraulic tank by means of gravity.

Hydraulically operated elevators enable:

  • Transmission of great forces

  • very precise drives

  • Realization of complex hydraulic circuits. The valves control driving comfort by progressively accelerating or decelerating the car and maintaining the nominal speed.

The Positioning system consists of the tank in combination with the accessories:

  • A slide in the hydraulic circuit that serves as a manual control valve that regulates the downward movement of the elevator.

  • A hand pump that allows the elevator to move upwards.

  • A shut-off valve as a safety device to prevent free fall. The shut-off valve intervenes automatically if the nominal speed is exceeded by 0.3 m / s.

There are several types of hydraulic elevator systems.

They differ in the number and type of cylinders or pistons, which in turn are assembled from a different number of stages. The more steps, the higher the telescopic piston.

There are two common types of application, which are again installed in two different ways. This depends on the distances the elevator has to cover or the structural requirements.

The counterweight is dispensed with in all hydraulic elevators.

  1. The simplest solution is preferred for short journeys. A cylinder is inserted into a hole in the ground. This lies in the middle of the pit and acts on the lower cross member of the frame. The prerequisite for this is the ability to drill deep enough into the ground.

  2. Since elevators rarely only have to cope with short distances, the most common installation method for a hydraulic drive is the one next to the elevator car. Like a forklift truck, the car lies on a crossbeam, which in turn is attached to the telescopic cylinder. The cylinders are housed in the side shaft.
    Telescopic pistons with 2 or more elements are usually used to take advantage of relatively long driveways with the same space requirement.

    This saves you having to drill holes in the shaft pit to accommodate the cylinder. In addition, the entire space requirement is limited to one side of the elevator shaft. With this type of construction, elevator manufacturers remain flexible when it comes to choosing the car design and accessories.

    The suspension coefficient, i.e. the ratio at which the elevator car moves in relation to the tip of the piston shaft, is 2: 1. But we have already realized suspension coefficients with 3: 1 and 4: 1.

    The most frequently installed hydraulic elevator consists of a cylinder / piston, which is housed in the side of the shaft with a pulley installed at the end of the shaft. These Elevator system is designed for the most common speeds and is preferred for 3 to 6 floors. The sheave acts as a simple pulley block through which the elevator ropes, which are fixed to the floor, are deflected and attached to the cross-beam in order to carry the lift car on top. In comparison to the direct drive, this achieves twice the travel distance at twice the speed. This construction is called inverted suspension and the drive is called indirect-lateral.

ADVANTAGES OF HYDRAULIC LIFT SYSTEMS

Little need for space:

  • More space creates more flexibility and more freedom in the design of the elevator system.

  • By dispensing with the counterweight, elevators with entrances from up to 3 sides can be implemented.

Flexibility in positioning the control unit and the hydraulic actuator unit:

  • The space for the control unit and the hydraulic actuating unit does not have to adjoin the lift shaft.

  • The room doesn't even have to be nearby. Hydraulic lines can be implemented over relatively large distances.

Subsequent installation of an elevator or an elevator system:

  • The entire weight of the hydraulic elevator is relieved on the foundation of a building. This even relieves the building structure.

  • Inexpensive to use.

For the most common distances:

  • By dispensing with the counterweight and its guides, as well as the possibility of installing all mechanical organs together in one of the lowest floors and being able to connect the actuating unit and the cylinder relatively easily with a hose, costs can be saved.

  • If the distances of the most common speeds are taken into account, hydraulically operated elevator systems are cheaper for the most extreme distances used.

Low energy consumption:

  • The downward movement of a hydraulic elevator is always done by gravity, so no energy has to be used.

DISADVANTAGES OF HYDRAULIC LIFT SYSTEMS

Low top speeds:

  • So-called turbo lifts, which are primarily used in high-rise buildings, only reach their speeds with a cable drive and counterweight.

Relatively short process paths:

  • Telescopic cylinders can only be expanded to a limited extent. Hydraulic lifts or elevators will therefore never be used in a high-rise building.

Higher use of performance:

  • During the upward movement of the car, a hydraulic elevator requires more power than a rope-operated elevator due to the lack of a counterweight.

Use of mineral oil:

  • In Germany, mineral oil is only used under the strictest of specifications and environmental requirements.

  1. when transporting hydraulic oil

  2. when using hydraulic oil (flammable)

  3. when disposing of hydraulic oil

Solutions without a machine room MRL (Machine Room Less) have also been developed for hydraulic elevators and hydraulic elevator systems. Control devices and lifting machines are used in a cabinet or inside the lift shaft.

You too can benefit from our bundled level of knowledge by choosing METROPOL AUFZÜGE GmbH for elevators.