Worm Drive
Worm drives (or worm gear sets) are ideal angled drives and are used in screw jacks where in fact the input shaft reaches right angles to the lifting screw. Other types of right position drives are bevel gears, and hypoid gears. Worm drives satisfy the requirements of several systems and provide a compact method of decreasing speed whilst increasing torque and are therefore ideal for use in systems utilising e.g. lifting equipment in which a high gear ratio implies it can be driven by a little motor.
A worm drive consist of a worm wheel and worm equipment also called worm screw or simply worm. The worm steering wheel is similar in appearance to a spur gear the worm equipment is in the type of a screw generally with a flank position of 20°. The worm gear screw can be one start or have multiple starts based on the reduction ratio of the gear set. The worm includes a relatively few threads on a little diameter and the worm wheel a big number of teeth on a big diameter. This combination offers a wide selection of gear ratios typically from 4:1 to 300:1.
The reduced efficiency of a worm drive lends itself to multi start worm gear applications that require intermittent instead of continuous use. The worm drive inefficiency originates from the sliding contact between the 
teeth. Appropriate and sufficient lubrication must be applied to dissipate the heat produced and reduce the wear rate. For long life the worm equipment it made from a case hardened steel with a ground end and the worm steering wheel is often made from bronze or cast iron. Other material combinations are used where suitable and in light duty applications modern nonmetallic materials are deployed.
Worm Gear Assembly
Multi-Start Threads and Self-Locking
Often a screw system (such as that within a screw jack) is required not to ‘back-drive’ when the holding force is removed and an axial load is applied. An individual start thread is commonly used in these situations as the shallower helix angle causes higher friction between threads and is generally sufficient to avoid slippage. Such a system is reported to be self-locking. This assumes a statically loaded program with little if any vibration as this may cause the friction angle to be conquer and the mixture to untighten. In systems that are at the mercy of vibration a locking mechanism or brake is advised to prevent back-drive.
If self-locking is not a requirement of something but a greater speed of translation is then a multi begin thread may be used. This implies that multiple thread forms are manufactured on the screw shaft.
Single Start Thread: A single helical thread shaped around a screw body. For every 360° revolution of the screw, the proper execution provides advanced axially by the pitch of one thread. This has the same value as the pitch. Regarding a single start thread, lead and pitch are equivalent.
Double Begin Thread: Two thread forms. During 360° revolution the forms progress axially by the combined pitch of two threads. Lead is normally 2x the pitch.
Triple Start Thread: Three thread forms. During 360° revolution the forms advance axially by the mixed pitch of three threads. Lead is definitely 3x the pitch.
Single Begin Thread, Double Begin Thread, Triple Start Thread
A multi start thread has a steeper helix angle which outcomes in less friction between your threads and therefore such a system is less inclined to be self-locking. It follows that a steeper helix permits faster translation along the threads i.e. an item utilising a multi begin thread can be tightened in fewer rotations than one utilizing a single start thread.
Worms are the driving gear in a worm and worm equipment set. Effectiveness of worm equipment drives is dependent to a large level on the helix position of the worm. Multiple thread worms and gears with higher helix angle prove 25% to 50% better than single thread worms. The mesh or engagement of worms with worm gears creates a sliding action leading to considerable friction and greater loss of efficiency beyond other styles of gearing. The use of hardened and surface worm swith bronze worm gears increases effectiveness, but we’ll make them out of just about any material you specify. The amount of threads on a worm and the number of teeth on a worm gear will determine the ratio of your set. Ratios are dependant on dividing the amount of teeth in the apparatus by the amount of threads. Typically the amount of threads on a worm are 1,2, and 4, but 3, 5, and 6 are out there as well. To regulate how many threads are on your own worm just look at it from the best where the threads begin and count the amount of starts.
Incorporating various multi begin threaded worm shafts directly into Ever-Power screw jacks escalates the linear output speed range we are able to offer.