Worm drive is a transmission mechanism for the movement and power conveyance of the two shafts, angle between two shafts usually be a arbitrary value or 90 degree. With the advantage of compact structure, large speed retio,stable transmission and reliable self-locking under a certain conditions, it is widely adopted in many machine and equipment.But it disadvantaged as low transmission efficiency and frequent consumption of nonferrous metals.
Commonly used to reduction gear,worm shaft might exceptionally adopted in speeder. Recently, with the higher power of the machine, many new worm driven system occurs and the disadvantage of low efficiency has been gradually improved.
Features of screw jack & structure
With the large speed ratio and small quantity of parts, such structure characters compacted and two tooth surface contacted by line contact, which serve a larger loading capacity than cross screw gears which also inside the worm drive system.
With continuous helical tooth designed of the worm, it gradually entered and withdrawed from the meshing with that of worm gear. The situation of its most gears meshed offers the product advantages of a small impulsive load, a stable transmission and a low noise. When the spiral angle of the worm is smaller than the equivalent friction angle of the meshing surface, the worm drive enjoys self-locking property.
When the lead angle of the worm is less than the equivalent friction angles of meshing teeth,the worm owns the property of self-locking and that in a reverse way. For example, for the heavy machinery self-locking worm gear, reverse self-locking plays an anti-counterfeiting role while it also suffers a low transmission efficiency and a harder abrasion, relative sliding speed between the teeth engaged by the worm,friction loss and efficiency are low. On the other hand, the large relative sliding speed causes the severe wear and heat on the tooth surface, usually, expensive materials are adopted to resist friction and wear.Good heat dissipation of lubricating device helps to reduce wear, so the cost of the worm is higher.