Automotive Two-Post Lifts.

Two-pillar lifts in for many years are the most popular group of lifts among car shop owners. The popularity of these lifts is due to the versatility of their use, the relative ease of installation and fairly affordable prices.

All types of double-column lifts can be divided into two main groups, depending on the transmission of the drive:

- electromechanical;

- Electrohydraulic.

In both cases, there are different ways of transferring the drive from the electric motor to the trolley lifting the serviced car.

In electromechanical lifts, lifting of the elevator arms is performed by replacing the rotational motion with the forward motion using the rotational motion of the cargo screw with respect to the stationary working nut.

In electrohydraulic lifts, lifting is performed by creating hydraulic pressure in the drive system.

All lifts of both types can have one drive for both columns. In the case of one engine, there is a need to transfer the drive from one column to another, and to ensure synchronization between them. Two engines - one on each column only require synchronization of traffic.

In the case of a single common motor for both columns, two-post electromechanical hoists differ from each other by the transmission of the drive between the columns (screws) and the synchronization type of the movement of both carriages lifting the car. Synchronization is achieved by simultaneously driving both screws using a chain. Depending on the design, it can be:

- above, above the columns (this leads to a reduction in the maximum height of the car);

- below, at the base of the lift (increases the total height of the ladders on which the car approaches);

- in the groove under the floor (significantly complicates the construction and installation of the lift).

Unfortunately, this solution is relatively noisy during operation and requires regular monitoring of the lubrication of the cargo screws.

The second, though less commonly used, method of transferring the drive from one column to the other with only one engine is the use of an angular gear in which the lower part of each screw is connected by a propshaft. In this case, the entire drive system is located below the frame on which the columns are mounted.

New, increasingly used designs with two engines - one on each column and the electric synchronization of the turns - have no problem with the transfer of the drive to the second column, and are more convenient to operate, which is more acceptable for car repair shops.

In terms of the advantages of electromechanical lifts, the more useful solution for car-care centers are electro-hydraulic lifts. Lifting in this case is realized by using two power heads located in the columns of the lift.

In the lifts of this type, the connection between the hydraulic drives between the columns (the motor is on one of the columns) and the synchronization of the work of the power heads in both columns can be carried out either at the bottom of the elevator (at the floor level) or at the top (at the height of the column end). Both solutions have their pros and cons.

When using the lower base located at the floor level, the total height of the lift is reduced. The absence of a connection between the columns in height makes it possible to service higher cars. The only restriction in this case is the height of the car workshop. Not in favor of such a decision is the fact that every time you need to run into and out of the workplace.

In addition, in the currently produced lifts, the bases are very low and relatively short, in the maintenance of a car with low clearance there is a difficulty with collisions.

Lifts of this type, despite the very short and low base between the columns, are not suitable for use in straightening and painting shops. It is difficult to imagine a raztovochnoy frame hitching or a cart together with the car located on it at least through the minimum threshold. When using the joint at the top between the beam-shaped columns, the main advantage is an ideally flat move.

Due to the failure of the connection of the columns of the elevator, the optimal working conditions at the service station were obtained in the lower part. To drawbacks of this type of construction, it is necessary to include a large minimum height of the car workshop (about 1-15 m in relation to the lifts with the bottom base), which is from 4 to 4.5 m.

Moreover, from the point of view of the location at a constant height (about 4 m) of the upper beam connecting the columns, maintenance of high vehicles is difficult. On the upper beam there is a limit switch, which protects from too high a lift of the car with possible damage to it.

In two-post electrohydraulic and electromechanical lifts, the car is lifted by two pairs of shoulders, fixed on carriages, moving along a vertical guide column. The shoulders are attached to the carriages in such a way that there is the possibility of a partial rotation in the horizontal plane and during the installation of the car on the post they could be removed.

The shoulders rotated on the head of the hoist are adjustable along the length through the extension from the shoulder fixed on the head of the smaller arm with the stop element (the lifted car).

Thanks to the so designed shoulders it is possible to safely and steadily lift cars with different body sizes and different points of the stop placed by the manufacturer.

To prevent damage to cars during lifting, the shoulders are equipped with paws with rubber tips (adapters), which are attached at the points of contact of the body with the lift. Paws also have the task of increasing the stability of the vehicle being lifted and damping the transmission of vibrations from the operating lift while lifting or lowering the car.

The design of the paws of the shoulders is essential for the functionality and suitability of all two-post lifts in the workshop. The design of the paws influences the minimum clearance of the car, under which the shoulders of the lift are wound. In most constructions, the height of the legs is 130-150 mm or more.

Two-post lifts can be produced in two versions:

- symmetric;

- asymmetric.

The symmetric lift has four equal arms, and the center of gravity of the vehicle being lifted is between the posts in the axis of their symmetry.

In asymmetric lifts, the arms of each of the racks (in pairs) have a differential length, the columns are facing towards the entrance, and the center of gravity of the lifted vehicle is displaced.