Adjusting the backlash on a worm gearbox primarily involves altering the distance between the worm and the worm wheel or using specialized components.
Adjusting backlash is crucial for maintaining gearbox precision and performance. Excessive backlash can lead to inaccuracies, vibration, and increased wear, while insufficient backlash can cause overheating and binding.
Common Methods for Backlash Adjustment
Based on standard practice and the provided reference, there are two main approaches to adjusting or eliminating backlash in a worm gearbox:
1. Modifying the Center Distance
The usual method of adjusting the backlash of a worm-gear assembly is to modify the center distance between the axis of the worm and the axis of the worm wheel.
- How it works: By slightly increasing or decreasing this distance, the meshing depth of the worm and wheel teeth is altered, thereby affecting the clearance (backlash) between them.
- Practical Considerations: As the reference notes, once assembled, such adjustment requires a major rework of the gearbox housing. This makes field adjustment of backlash via center distance modification very difficult and often impractical without disassembling and potentially remachining parts of the gearbox.
2. Utilizing Specialized Components
For applications where zero or minimal backlash is critical, specialized components are used:
- Spring-Loaded Split Worm: One method for eliminating the backlash is to use a spring-loaded split worm. The worm is split axially, and a spring forces the two halves apart. This forces the teeth of both halves to engage tightly with the teeth of the worm wheel from opposing sides, effectively taking up any clearance.
- Spring-Loaded Split-Worm Wheel: Similarly, a spring-loaded split-worm wheel can be used. The worm wheel is split, and a spring forces the two halves to maintain constant contact with the worm threads from both sides, thus eliminating backlash.
These specialized components are designed into the gearbox during manufacturing and provide a way to maintain minimal or zero backlash continuously, often compensating for wear over time.
| Method | Description | Practicality (Post-Assembly) | Result |
|---|---|---|---|
| Modifying Center Distance | Altering distance between worm and worm wheel | Difficult (Major Rework) | Adjusts Backlash |
| Spring-Loaded Split Worm | Worm split axially, spring-forced contact | Integrated into Design | Eliminates Backlash |
| Spring-Loaded Split Wheel | Wheel split, spring-forced contact | Integrated into Design | Eliminates Backlash |
In summary, while the fundamental principle of adjusting backlash involves changing the center distance, performing this adjustment on an assembled gearbox is complex. Specialized designs incorporating split, spring-loaded components offer a more practical method for achieving zero backlash in performance-critical applications.
