Know How to Adjust Gearbox Backlash

Gears are an integral part of any machine, automobile, and so on which facilitate controlled motion and speed adjustment, irrespective of the type of motion such as linear, rotational, and so on. Backlashes are essential for the smooth rotation of a gear. It offers many benefits such as facilitating lubrication. It forms a clearance and creates space between the mating teeth of the gear. This space allows for oil to lubricate the gear and prevent friction. However, this same space may mismatch the speed or cause loss of motion between input and output shafts. This poses challenges in terms of accurate positioning in machines, equipment, and so on. Hence, the gearbox backlash needs to be adjusted or even eliminated to some extent. This post discusses details on gearbox backlash adjustments.

Gearbox Backlash Adjustment Explained

While lubrication and space between the gear teeth is essential to some extent, this is the very reason for the backlash, primarily. So, logically, it is essential to reduce this distance. This gets the teeth in a tight mesh and helps reduce disparities or variations in terms of bearing capacities, distance between the centers of the teeth, and dimensions. There are various types of backlash and the adjustment to be done depends largely on this factor. Another important factor is reducing the tooth thickness. The tooth thickness reduction would depend on your manufacturing and machining accuracy requirements. Here are some useful pointers regarding backlash adjustment or elimination.

• Although it depends on the number of teeth in each gear, it is quite common to consider half allowance in most cases. However, specific gear types and other factors need to be considered.
• In helical gears, the depth of the teeth is usually higher than the standard one as it lets the hob sink well.
• In case of rotating gears, circumferential backlash is required, which is equivalent to the length of the arc. When the gear keeps rotating, at one point the mating gear becomes stationary while the meshed one makes contacts. The gear distance is based on this factor.
• Angular backlash is required to facilitate maximum angle for proper gear movement, even as the mating gear is stationary.
• Likewise, you have axial and radial backlashes, wherein the displacement of space is done such that the meshed teeth of each of the gear pair come in contact.
• Sometimes, backlash also occur due to manufacturing and assembling defects, bearing, and mounting issues. In such cases, certain precision speed reducers with the help of tight tolerance parts help reduce these issues. This is especially applicable in precision instruments.
• Modifying a gear design to reduce backlash is also a widely used option. In this, the meshed teeth distance is shortened right in the design stage.
• Through split gears, you can completely eliminate backlash. Here two gear halves are placed adjacently, wherein one half rotates and the other is fixed onto a shaft. This helps completely cover the space of the mating gear tooth and hence eliminate backlash. However, this arrangement is fine for low to medium load applications.
• Special gear designs are made for specific applications which require extremely low backlash. Here, instead of conventional gears, they may use traction drives, nutating systems, and so on. They perform motion in a different manner and help reduce backlash.

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