Premise:

Worm wheel sets have the advantage of having low ratios with limited size. Worm wheel sets allow having just one coupling and, as a consequence, only one backlash between the teeth to control.
Starting from this premise, we have developed the technology to manufacture worm wheel sets with adjustable backlash with Double Module-Geometry.

With this manufacturing system there are no limits to the ratios we can obtain. Manufacturing follows the same process as for normal worm wheel sets.

The characteristics of our production allow us to "personalize" your set. Therefore, we can manufacture "custom" worm wheel sets with adjustable backlash to your drawings.

Adjustable backlash system:

Often you use variations of the distance between centers with ground and settled eccentric flanges creating coupling problems. You notably reduce the contact area and the consequential wear, meaning more frequent adjustements with additional costs, decreases.

We believe that you should use normal profile geometry and avoid all other adjustable backlash systems, dividing the wheel in half for or dividing the worm gear in two.

The backlash adjustment system that we propose allows the best coupling between two gears.

To obtain these results on both the worm and wheel gears, two different steps are taken: the worm gear has a variable and continuous tooth thickness and the wheel gear has toothed section and asymmetric teeth.

Operating in this way, you are certain to have corresponding angles that remain coupled after settling.

The axial translation of the worm gear allows the backlash to be adjusted to the desired point.

Suggestions for applications for Worm Wheel sets with Adjustable Backlash

Engineering:

To correctly engineer a worm wheel set with adjustable backlash, you must precisely establish the measurements and the worm wheel set's overall design. The design must show the original assembly measurement (W) and the worm shaft's translation direction for the adjustable backlash.
The backlash is adjusted with the worm shaft's axial translation: we suggest an axial backlash translation of 1/10 of the length of the worm shaft.
To avoid reversing the position during assembly, the bronze worm wheel must be asymmetrical.

The housing: all the adjacent elements must be precision machined and assembled with the worm wheel set with the possibility to adjust them during assembly. During assembly, we suggest boring the housing with a tolerance of 5 Js of the distance between centers.

The Worm Shaft: after assembly, the teeth area will protrude compared to the worm wheel; then, with adequate run in, the worm shaft will "retract" and it will retract more and more with the backlash adjustements prescribed for maintenance.

The Worm Wheel: the worm wheel' s assembly must be tight. Mounting wheel to the hub must be slightly forced (tolerance: shaft k, m and hole H). We suggest heating the worm wheel to 70°C.

The Mounts: they must have the possibility of the axial translation with spacers or locking rings (Example A - Example B). For the worm shaft support, you can use normal pre-loaded ball bearings. Axial adjustement must be possible on the mounts as well as the worm wheel, so you can avoid disassembling of the entire machine.

Example A

Legend:

• 1-2: ball bearing with "O" arrangement and axial blocked
• 3: free axial ball bearing
• A: opposed locking ring
• B: locking ring
• C: screw

Worm wheel set / Page 2

All the gear units showed in this brochure have been engineered and manufactured by our technical department according to our Customer's needs.