3 point vs 5 point rapid traverse cam

TOS Trenčín introduced the rapid feed traverse on their SN lathes, specifically on the late version of the B model. The main components of the first rapid feed was the evolved worm 883036, the 3 point cam 883147, the bushing 883035, the gear wheel 883025 and the worm gear 807049.

With the later B models and early C models, the design of the parts has changed. The main change occurred on the worm 883439,  the 3 point cam 883440, the gear wheel 883436 and the bushing 883442. The gear wheel 807049 was kept the same on all SN lathes until the end of the production in 2024 (all lathes SN32C, SN40C, SN50C, SN63C, SN71C, SN400, SN500, SN630 and SN710). Although the gear part number later changed to 883028, it is still the same wheel.

What has created some confusion on the late B and early C version of the SN lathes is the update of the 3 point cam. Whist the early version of the rapid traverse had a 3 point cam 883147 with an inner diameter of 42 mm, the newer version of the rapid feed had a 3 point cam 883440 with an inner diameter of 40 mm. The C model of the rapid feed traverse was updated to the 5 point cam 883443 with an inner diameter of 40 mm and the production of the cam 883440 was discontinued.

The number of cam points (3-point vs 5-point) has no impact on the functionality or compatibility of the rapid traverse system. That is why it is important to check the inner diameter of the cam not the number of points before ordering your new spare parts. The critical parameter is the inner diameter of the cam (40 mm vs 42 mm). A good clue is also the check the worm and the bushing. Also note that the 5 point cam 883443 is the same across all SN C models SN32, SN40-50, SN63-71, as well as SN400-500-630-710.

What is the difference between 3-point and 5-point cam?

The number of points does not affect functionality. The key parameter is the inner diameter (40 mm vs 42 mm).

How do I know which cam I need for my SN lathe?

Measure the inner diameter and check the worm type. Model alone is not reliable.

Are 5-point cams compatible with all SN lathes?

Only with 40 mm systems used in C models and late B models.

Is worm gear 807049 interchangeable?

Yes, it remained unchanged (later renamed 883028).

40 mm inner diameter 5 point cam

42 mm inner diameter 3 point cam