RC Car Crawler kingpin angle and it’s positive and negative effects and influences

What is kingpin inclination?

In general, the fixed kingpin of most vehicles steering structure (including real vehicles and models) is not vertical to the ground. From the structural design drawing of the real vehicle, we can find that there is a certain inclination angle between the steering cup and the vertical axis. This angle called kingpin introversion. The function is to make the front wheel automatically return to the positive position during the driving, and simple operation to reduce the impact force of the steering wheel, making the vehicle running in a straight line stably and much easier.

In addition to the kingpin incline, a back tilt of the kingpin is also generally designed. The larger the kingpin Angle, the more stable the front wheel alignment, but the steering wheel rotation will be more laborious (usually the kingpin Angle is not more than 3°).

The kingpin rear-angle is more obvious on Harleys, and the larger rear-angle makes it easier for riders to drive long distances in a straight line.

The negative effect of kingpin Angle

We already know the kingpin Angle and the positive effect, but what about the negative effect caused by the kingpin Angle? First let's look at a funny little animation.

You can see: when the axle is fixed, the wheel turns to the right, the right wheel fell into the ground below, and the left wheel left the ground, left to the opposite.

This is a phenomenon with a standard kingpin Angle. Because after the tilt of the kingpin shaft, the intersection point with the ground in the steering process is no longer vertical, the difference increases with the increase of the steering Angle. When the steering Angle is 0, the difference is also 0

So will the wheel actually sink below the ground, will the wheel lift off the ground?

Of course it didn't, so we looked again, adding gravity and ground forces factors. The actual situation is like this: the axle has rotated and tilted, which can also be understood as the body has tilted. This tilt amount is not only affected by the kingpin Angle, but also the size of the steering Angle, wheel diameter (offset Angle amplification), and so have the influence. So if we look at crawlers, mostly on slopes, what's interesting about them?

This is the slope on the direction of turning uphill, the axle (body) to the downhill direction of tilt, reducing stability.

This is the slope turning downhill direction, the axle (body) to the uphill direction of tilt, improve stability.

Therefore, many structural points have positive and negative effects, and some phenomena are not influenced by a structural point. This is also true of real cars. By understanding these characteristics, various phenomena that occur during vehicle tuning or actual driving can be answered.

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(Supercar is specialized in designing and manufacturing for radio controlled cars and car accessories. As an ISO 9001 certified manufacturer, Supercar produces a comprehensive range of 1/18, 1/12, 1/10, 1/8 and 1/5 scales of RC cars and product line covers 4WD racing buggy, desert truck, truggy, monster truck and short course truck, crawler etc, and meanwhile providing you high quality spare part and hop-ups)