Braking force

Please see picture attached.

We've talked alot about angles of the actuators.

But I think the biggest force against a actuators is the body itself.
If you have a modified brake when you need to press harder to achieve full brake force then there is more force from the back of the body against the actuator.

Think about it next time your racing. Feel your back pushing against the seat when you brake hard and keep it pressed.
People with rubber block modified brakes, andy pastore, nixim brake mod or maybe better breaking systems on the market will know this.

Maybe this is why some people actuators fail and the others don't. People have different driving styles and brake alot harder and cause thier body to push the seat against the actuator, resulting in increase wear & tear and some case pin brake.

This is a valid concern for DIY seat bases.

As with any engineering project, many aspects of a simple seat base can be optimized for performance. If the actuator angle is too great then you will actually be fighting the actuators under braking. However, with the proper seat height to pedal ratio and actuator angles, much of the force that you apply via pedal pressure can be translated into radial load on the actuators instead of stress on the motors. It a bit of a balancing act because too much of either can cause problems.

There are many things that can impact this such as:

-Pedal angle
-Pedal Height
-Pedal Strength
-Seat Height
-Actuator angles
-Actuator angle mounting style

If the actuator angle is too great then you will actually be fighting the actuators under braking.

You mean if the actuators are too upright like the frex design?

you can have force against actuators bar from side on or force applying on top of the actuator rod if you know what I mean.

This is definately something I have run into when I switched to using a load cell brake. By adjusting the actuator braking travel and lad cell brake pressure I have been able to find a happy medium but it is a balancing act as Berney mentioned.

You actually don't need to calibrate your load cell to require too much pressure to get a realistic braking feel so I would start by reducing braking pressure first before adjusting the actuator or seat parameters.

I think the braking technique can be a factor as well.
Applying the braking force by using the upper part of your back is less favorable, than using the hip to counter the force that is applied to the feet.
It's a little bit hard to explain in words.

But by applying the braking force from the hip to the feet, the force vector is closer to the pivot, and the therefor the stress applied to the actuator is fewer.

Changing the angle of your pedals (>vertical) might help a little bit as well.

Btw, the closer the bum is to the pivot, the better it is, so check if you can reduce the distance from your seat to the pivot.


regards

Actually the opposite. If I were to alter my design to have even more actuator angle, it would allow the braking pedal force to more directly oppose the actuator motors. TO take this illustration to the extreme, imaging if I went so far that the actuators were horizontal behind the seat.

A more vertical design like Frex causes more radial load on the actuator arms (for illustration purposes, you can imagine the forces would be trying to bend the actuator rod because the rods are vertical and the foce is horizontal). Extensive radial load can result in premature bushing wear in the actuators.

IMHO, the actuator angles that I have proposed to the community some time ago are a good compromise for 150mm SCN5 type sims.

egoexpress has a good point also. You can choose when braking whether or not you are going to arch your back. If you are your back, you will create more actuator stress since your contact point with the sim is higher on the seat creating more leverage. If you do not arch your back, the contact point will be your hips and less of your braking force will be translated to the actuators.

I`ve noticed that as well when i had pedals on the floor:

- when i had them closer to Simulator then it did not affect, because i was pressing down. When i moved them far and start pressing to the front it changed a lot (opposite force).

Actually it doesn`t matter in case of project where pedals are on moving platform.

I know what you mean egoexpress:

two ways you can feel pressure when braking.

1. on higher back (shoulders)
2. lower back (hip section)

Natural way is 1: (imo)
With thought & practise you can learn to brake using hip pressure 2:

thanks bvillersjr: I think the way my sim will be setup when all done will have the scn5 more upright than yours. Also my pedals are mounted like the way i did the picture on top post. So basically my simulator won't be setup right i think.

I cannot change actuator angle as they will mount to the frame steel. i suppose ill just make the pedals really sensitive so i dont feel my back pushing against the seat. I'm sure there is always ways but i thought it is important topic to bring up.

hi you can use rubberbands front under the seat.i use a vpp paddels with
hydraulic mod from motopc and with the hydraulic mod i have the same problem on my old sim bud with the rubberbands is works very good.

Hi !
In reply to the idea in the first post : an easy idea that I saw in a video.

When braking, the seat move forward.
So, if harness is attached to a string to the bottom fixed structure : the movement will tighten the string, hence applying a force on harness to our body. This should give the feeling of braking.

That's the idea !
Mat

Another way is a dc motor on the back pulling on the belts all controlled via the sim software my preferred method