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Systema questions & answers

by News Fairy

Systema have been answering some questions about their products:

SYSTEMA Major Dealers

I always send questions and answers with dealers. I hope it is helpful for you as bits of knowledge. Please read when you have time.

Also in the future, I will send whenever I have something.

Thank you as always.

Best regards,




What differs between the worm gear and the conventional gear? ? ?

Reply of our factory

Since I received the question about the difference of the worm gear and the general gear, I answer.

The basic engagement of spur wheel which is the standard of the gear is line contact, and worm gear / helical gear  / screw gear is "sliding" based on point contact.  It is the big difference.

Generally, compared with the spur wheel whose maximum engagement rate is low, the gear of sliding such as the helical gear has less noise. It is more suitable for use by high rotation.

However, our failure was based on shortage of the transfer power of the worm gear. it differs a little with above theory.

As being published on the report, since the space for the P.T.W. gears BOX is too small, we depended on the feature that we can get big moderating ratio with the one step of the worm gear, which was the cause of failure.

However, since we guess that there is possibility for improvement such as cutting by double, we would like to realize it someday.

We are persistent for such technique.  (Smile)

Further Question

The contact of the point has stronger transfer power and less frictional resistance than the contact in the line.

Nonprofessional like me tends to think the line with larger contact area has more transfer power and frictional resistance.

Reply of our factory

Since there is a misconception, I explain more.

It is not the difference of the contact of point and line.

Engagement of the gear is theoretically the line contact of the tooth trace.

The gearing frictional resistance value of gears which engage mutually, can be calculated from the engagement rate (contact portion which has engaged simultaneously) and face width (dental thickness)

Of course, this is the theoretical value, so the twist or bending of the shaft for supporting the gear or the gear BOX which are generated by dynamic load are not included.

Roughly, if engagement of the spur wheel is "the transfer to strike", helical gear and the worm gear is "the slippery transfer. "

Generally, since t the helical gears have higher engaging rate, transfer power is larger. On the other hand, the resistance becomes higher. Paradoxically, with the same transfer power, we can design by the smaller module.

In addition including the object for the cars, rotation is smooth, and generating of vibration decreases.

In the case of the worm gear, the engagement rate can be higher than the helical gear, but the axial angle cross at right angles, resistance becomes very high, and transfer power decreases.

So, we need to use our ingenuity during production such as cum shape.

I am sorry for unclear explanation.

By the way, most excellent gears are for cars.

They produce the gear blank the most high-precision in order to increase the engagement rate. They design the smallest module for the load in order to lower the frictional resistance value, and polish the tooth surface after heat treatment.

The surface roughness is about 6.5S / MAX. It is the result like a monster.


On this day..

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