High-Speed Screw Jack

1. How does a High-Speed Screw Jack work?

A High-Speed Screw Jack, or Bevel Gear Screw Jack (KH), is used to convert rotary motion into linear motion. The rotary motion generated by a motor is redirected through the bevel gear and transferred to a spindle. Combined with a threaded nut, this setup creates linear movement. There are two types: the traveling nut version (where the spindle rotates and the nut moves along it) and the basic version (where the spindle moves while the threaded sleeve in the gear rotates). The performance and force parameters remain unchanged.

Learn more about the traveling nut version vs. the basic version here: How Screw Jacks work and where they are used (grob-antriebstechnik.de).

In the High-Speed Screw Jack, there are two bevel gears that redirect the torque or rotary motion by 90°. The driving bevel gear is mounted on the drive shaft, while the outgoing bevel gear houses the spindle sleeve. By varying the sizes of the bevel gears, different gear ratios can be achieved. Standard options include gear ratios of 1:1, 2:1, and 3:1.

2. Sizes and options

The sizes cover the load range from 15 kN to 90 kN with the following models:

1. KH090
2. KH140
3. KH230

Options include the choice of one to four drive shafts, which can eliminate the need for additional gear reducers in a Multi-Jack System. The various options allow for mounting on a wide range of system interfaces. Additionally, options such as bellows, motor bell housings, complete stainless steel versions, flange nuts, motors, spiral springs, trapezoidal and ball screw spindles are available.

3. Why should I use a High-Speed Screw Jack?

When compared directly with worm gear lifts, significant differences become apparent. The components used for redirection in bevel gear drives are bevel gears, which offer two main advantages:

✅ High Efficiency: The teeth of bevel gears transmit the applied torque through rolling friction, achieving an efficiency of over 95%. This results in minimal energy losses, allowing for a duty cycle of up to 100%.

✅ High Speed: The low power losses also enable high speeds for axial movements. Speeds exceeding 100-150 mm/s are easily achievable in combination with ball screw spindles.

4. When should a High-Speed Screw Jack be chosen?

These drives are especially suitable when the application requires continuous adjustment or high cycle times from the lifting element. They excel in high-speed applications. In combination with a ball screw drive, the efficiency exceeds 85%, making them ideal for continuous adjustment in applications such as filling systems, assembly lines, and robotic feeders. A High-Speed Screw Jack is essential when the combination of:

1. High control and precision,

2. 30-100% duty cycle,

3. Predictable lifetime with ball screw drive

Advice for project planners: Clarify essential requirements with the customer. In some cases, worm gear lifts might be a better choice.

5. When is a High-Speed Screw Jack a poor choice?

Compared to Standard Screw Jacks, High-Speed Screw Jacks generally come with a higher initial cost, often 30-50% more. The more complex internal construction of the gear drive increases assembly effort significantly. Additionally, the load capacity of these drives is limited to 90 kN. Applications requiring higher loads may need either additional Screw Jacks or consideration of whether a Worm Screw Jack with standard speeds would suffice. The space-saving advantage of multiple drive/output shafts in High-Speed Screw Jacks is rarely the decisive factor for the higher initial investment.

6. Pro and Cons