Excellent spindles for lifting jacks
Nowadays lifting jacks are usually used for lifting rolling stock for maintenance purposes. This is done either by mobile or underfloor screw jacks all of which use trapezoidal spindles to carry the load. For the reliable operation of these threaded spindles, several factors need to be considered right from the start in order to avoid the dreaded stick-slip in the aftermath. The stick-slip is caused by two surfaces alternating between sticking to each other and sliding over each other, with a corresponding change in the force of friction. This can lead to vibrations that are emitted as noise ("squeaky" spindles) and in the worst case it can even lead to cold welding of the lifting nut and spindle – completely destroying the lifting jack.
Hans Gereke-Bornemann (Bornemann-Gewindetechnik, Managing Director): "If we are told of problems with lifting jacks, one can generally assume that one of the following factors is part of the problem: surface quality of the spindles, contamination inside the system, constructional faults or the selection of the lubricant. In many cases, the problem is a complex mixture of several of these factors. It is therefore important to consider all these factors already in the design phase in order to avoid the dreaded stick-slip effect.”
Manufacturers of lifting jacks can often not control all of the above mentioned factors when their systems are in operation,it is therefore of even higher importance to ensure that the surface quality of the spindles used is excellent. At low speeds and high pressures on the flanks the presence of a lubricant on the spindles is absolutely necessary in order to prevent the stick-slip effect from occurring. Bornemann spindles feature lubricating pockets on the flanks which help to keep the lubrication on the spindles.
Bornemann-Gewindetechnik provides threaded spindles for various applications in all kinds of industries. One focus of the production lies in the production of trapezoidal screw drives, consisting of spindles and nut sets for heavy-lifting equipment, such as those used in the field of lifting equipment for rail vehicles, in the theater or stage construction and special machinery. The standard sizes of screws are in the range of 10 to 180 millimeters in diameter and up to a length of 6 meters. Spindles can be delivered within 2-3 weeks after the receipt of the order.
