Why Bevel Gear Screw Jacks Have Higher Transmission Efficiency than Worm Gear Screw Jacks？
Sep 17 , 2025
The difference in transmission efficiency between bevel gear screw jacks and worm gear screw jacks mainly comes from their distinct meshing methods and friction characteristics. A worm gear mechanism works similarly to a screw and nut, relying heavily on line contact and sliding friction to transmit motion. Because of the high relative sliding speed, significant energy is lost as frictional heat. As a result, the mechanical efficiency is typically only 30%–50%, and even under precise machining and good lubrication conditions, it is difficult to exceed 60%. In contrast, bevel gears operate much like conventional gear systems. Their meshing involves point or near-line contact, with rolling friction as the dominant mode. Since relative sliding is minimal, the efficiency can reach 90%–98%, with far less energy loss compared to worm gears.
Transmission ratio also plays an important role. Worm gear screw jacks can achieve high gear ratios (such as 1:20 to 1:100), but as the ratio increases, the lead angle of the worm decreases, causing more sliding friction and further lowering efficiency. Bevel gears, however, typically operate within a smaller ratio range (about 1:1 to 1:5), which allows them to maintain high efficiency while also keeping tooth contact stresses at a favorable level.
Another key factor is self-locking capability. Worm gear screw jacks exhibit self-locking because the friction angle is greater than the lead angle, preventing the load from back-driving the worm. This feature eliminates the need for additional braking devices when holding a load, but it also means that energy cannot be transmitted back through the system, reducing efficiency. Bevel gear screw jacks, on the other hand, allow for efficient bidirectional transmission. They lack self-locking capability and usually require a motor brake or mechanical brake to hold the load, but they achieve much higher energy transfer efficiency.
From the perspective of heat management and service life, worm gear screw jacks generate substantial heat during operation due to sliding friction, requiring proper lubrication and cooling. Without this, wear accelerates and service life decreases. Bevel gear systems, by comparison, produce far less heat, demand simpler lubrication, and deliver stable efficiency over long-term operation, resulting in a longer lifespan.
In practice, worm gear screw jacks are better suited for low-speed, intermittent applications where load holding is important, such as stage lifts or valve actuation. Bevel gear screw jacks, by contrast, are ideal for frequent operation, higher-speed transmission, and applications where energy efficiency is critical, such as automated production lines and continuous-duty equipment.
