Our topic for today is “Steep climb and snow angle in Offroad” :
Yes, Dear Friends, this evening we will be doing a technical analysis of a steep climb we made during one of our weekend excursions.
Our first video on the subject is below. They are mostly images of the struggling process.
Our second video belongs to as long as the exit is successful.
There are necessary explanations on the attached pictures.
Note that in the first video, the vehicle had no problem driving up a steep slope, however, once it was suspended, it was no longer able to drive. Even in the most upright position, it can move back and forth briefly. This shows that there is no grip problem on the slope.
Off-road Basic Technical Information
Dear off-road and nature enthusiast friends, we are together with another sharing of our Off-road Basic Technical Information article series. The information I will provide; These are concentrated, technical-based, lived experiences, and some of the details that will find a name in the off-road literature for the first time. With the hope that it will benefit the readers.
The problem arises when the wheels lose traction, when it hangs. If there is no traction on the wheels, tire size, type, compound, middle, rear, front locks, pilotage, etc. are useless. Now, there may be those who think that they can get out of here with a good pilot. Piloting is useless if the tire is not holding the road. Piloting only makes a difference in not falling into that situation. This is a prediction that will develop with experience, when and what to do. In the second video, the output occurs as a combination of both methods. It continues on its way, both the upper corner has been rasped a little and it has reached the inertia that will enable it to pass the moment when the road grip is lost.
When we come to the top corner, because the snow angle is not enough, the chassis is sitting, the tire stays in the air or even if the vehicle is on the chassis, even if the shock absorber stroke is long, after a point, only the axle weight remains on the tire. At such a steep place, the traction that can only be provided under the axle weight is naturally not enough to drive the ~2.5 tons vehicle. The vehicle’s own weight should be transferred to the wheels as much as possible. Coilover shock absorbers will be able to make some difference.
In order to better understand the subject, I will recommend you to read our articulation article.
It was also possible for me to make the move I made in the second video the first time I entered the track and walk away. However, in this case, there would not be much reason to do the analysis we are doing now, and this would be one of the places we normally walk. So have some fun on the course without risk. This both increases the taste of the work and improves the experience. The goal here is not just to get out. Analyzing the conditions in detail, both to increase experience and to catch the overlooked points and share them with all our friends who are not on the trip.
The track is not a very short track, at least a track longer than the length of the vehicle. This requires us to be very careful at every point. It will be of great benefit to you to read our archive article on steep descent and steep ascent , in which the risks of steep ascents are evaluated.
The situation I will evaluate here is for the track that we are discussing. The situation is different in the beach-like straight driving track.
Avoid bouncing the vehicle too much. Especially on hard ground when the locks are not engaged and at high RPM.
As soon as the front tires of the vehicle are inflated, if the middle lock is not engaged or one of the rear wheels loses traction even if the middle lock is engaged, both of the front wheels or, since the moment of separation from the ground is different, one of the front wheels will be able to absorb all the power of the engine. If the vehicle is not 4L but 4H, this time, the speed of the front wheels will increase. We do not have a habit of braking when the vehicle is airborne, we continue to press the gas. This is a factor that will increase the rotational speed of the tire, not the speed of the vehicle. Also, if the front wheels fall on a ground with good grip after jumping, you may cut the axle or cause damage to the differential (such as stripping or breaking of the axle gears or spider gears, breakage of the axle shaft of the idler gears, breakage of the gear housing, etc.). (For example, if you are jumping from the steep dirt exit on the side of the road to the asphalt, and you can not increase the speed of the vehicle, this exit is loaded on the gas and you increase the speed of only the front wheels.)
The lower the speed of rotation of the rear tires of the vehicle and the speed of the vehicle itself, the higher the rotational speed of the front wheels, and after the front wheels reach this high speed, the torsion effect on the axles occurs due to both the low speed of the vehicle and the ground not allowing the tire to rotate. won’t be able to and will cut it. The differential side of the axle will try to turn, while the tire side will try to stop abruptly when it touches the ground.
In 4L, the situation is a little different. In general, in 4L vehicles, the middle lock is also activated. This will eliminate the speed difference between the front shaft and the rear shaft. However, when the front wheels are lifted into the air, if the rear wheels also slip and increase their speed due to both the general jumping tendency of the vehicle and the slippery ground conditions, this time when the front wheels touch the ground, the axle may cut again due to the higher transmission power of 4L, even if the speed is not very high.
In addition, the structure of the track can change after each pass, sometimes the vehicle driving in front makes the road, sometimes it breaks it. The channel formed while trying to make a trace in the video is filled and the corner is a little rasped and disappears and the risk of sitting on the stomach of the vehicle is reduced.
Conclusion and Suggestions:
Always be careful in the field, don’t drive loosely. You may not have noticed at the beginning how dangerous the track is, be alert at all times, and have an assistant guiding you if possible.
If the sudden change in load on the axle has an effect on the axle’s capacity, the axle cuts off. It is necessary to understand how this effect occurs and to avoid those movements.
Do not bounce the vehicle. While jumping may seem like fun, it’s probably the most damaging mode of use to the vehicle’s drivetrain. Be even more careful in this regard, especially on vehicles that have not been modified with stronger parts.
Best Regards,
13/05/2020