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Any chance this will work?

WaterH

WaterH

Well-known member
Joined
May 20, 2020
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So, Hydro-dynamic was working on a liner actuator to apply the E-brake. He had a thread on here. I was hoping he would supply part numbers for me to purchase. For whatever reason, he changed his mind and went with a more conventional setup. I guess that means the water head has to do it.

I have a sterling on my project with E-brakes already. So all I need is a couple cables and an actuator to pull em. I ordered a actuator and cable for one side to see how it would work. I didn’t want to spend a lot of time on this if it’s not going to work, so I rigged up a temporary test setup.

E40273B7-2BA0-4343-8150-B2FA284ACD1A.jpeg


The other end of the cable is hooked up to the brake. It was supposed to be the correct cable for this axle, but the end was slightly different. I just bolted it anyways for the test.

DA4080BD-D660-4543-AC0D-1633989C0B0E.jpeg


So I put power to it and it sucked it up. The thing is ratted at 330lbs. Pull. Not sure if that’s good. You obviously don’t push that hard on the E-brake pedal, but it has some leverage. In any case, it pulled hard enough to bend the cable bracket I made. It did move the lever on the axle. Tomorrow I’m going to jack up the truck and see if I can turn the wheel. Is there any standard for how much a E-brake should hold? (Like grade of hill?)

48DE9EBC-B1AF-4865-968E-AC9245794348.jpeg


Any predictions on how good this holds? Of course, if I put it on the truck, I would have two cables. Unless I get two actuators, it will have half the pull. Is there any reason I shouldn’t have two actuators?
 
If it bent the bracket it's. More then plenty for two cables. The stock brackets on my rig are 1/8th thick.

I think you need to figure out how much pull in inches of cable it takes on a stock rig to set the parking brake and match it.
 
Winchested said:
If it bent the bracket it's. More then plenty for two cables. The stock brackets on my rig are 1/8th thick.

I think you need to figure out how much pull in inches of cable it takes on a stock rig to set the parking brake and match it.
Click to expand...
The part that bent is 1/16”. You can see it in both pics. (Straight in the first, bent in the second)
 
What is the E-brake style? Is it a hat style system? Small drum brakes inside the rotor?

Then yes that is enough pressure.

For a Eldorado style caliper, which doesn't look like you are using then no it is not enough pressure.
 
I'm sure that will be fine for your rig.

You asked about testing standards; I remember watching a video a while back that showed the spot on the OEM test track where they tested the parking brake. It was a steep grade, and the standard was that the park brake should be able to hold the vehicle at max GCWR. The truck I saw being tested was a late model F350 with a fully loaded gooseneck trailer. They stopped on the hill, put the truck in neutral and then jammed on the parking brake. It actually skidded the tires for a few inches after the main brakes were released, but it held.

Again, way overkill, but I thought it was an interesting test.


EDIT - it was a 12% grade that they use. SAE J2807
 
So I jacked it up, spun the wheel. Then I powered up the actuator and spun the wheel again. Hmmmm.

Backed off the actuator. Pulled the little adjuster plug and turned the star wheel. (I’m not sure how much) The tire would still turn easy. Powered the actuator again and the tire was locked. Backed it off again and the tire was free. So far, so good.

Lowered the truck back on the ground. In newtrel, I could move the truck a foot pretty easy by grabbing the tire and pulling. So I powered the actuator up again and tried to move it. No chance.

My conclusion is this will work. I’m not sure if one actuator will be enough to pull both cables, but if worse comes to worse, I’ll use two actuators. Once I get it all done, I will transfer the tech to Hydro‘s thread since it is more searchable.
 
Depending on the design, drum brakes usually need to move a little in order to work.

so being able to spin them by hand when applied doesn't surprise me.
 
This thing moves 2”. That’s about the same as the lever at the wheel. Most of the brake cables I’ve seen (Fords) just have the two cables go to a bar and the cable from the front goes to the center of that bar. (Pulling both of them) Of course, if I do that, the force applied will be cut in half to each rear cable.

Can’t really use leverage because the actuator only moves 2” And that’s how far I have to move the lever. They do make some that travel further, but if I’m going to buy another, I will just run two duplicates.
 
I assume that thing has enough gearing to stay put without power?

Why are you doing this? Packaging? That actuator seems huger than a VW-style hand lever...
 
To calculate parking cable force:
Assuming a person can generate full body weight with one leg = 200lbs person = 200lbs at the pedal would be max design force, the average person would push with less than 100lbs to actuate the brakes.
Looks like the F250 pedal is around 2:1 so it can generate 200lbs of pull to engage the brakes
This is confirmed with some of the electric linear actuator brakes systems that are rated at 200 lbs although most actuators are rated to push and not pull so the rating goes down. Some actuators can not handle pull at all so be careful which ones you choose.

Make sure yours is rated at 330 pull and not push. Most actuators are rated push and if you pull too much the bolts for the housing and yokes can break or strip out and then you are rolling down the hill to your death.
 
subybaja said:
I assume that thing has enough gearing to stay put without power?

Why are you doing this? Packaging? That actuator seems huger than a VW-style hand lever...
Click to expand...

It looks to me like it is just a motor hooked to a screw. If the screw stops, it’s locked. (I haven’t taken it apart, so this might not be true) I would prefer the hand lever, but I made no provision for one. Now, the project is too far along and I don’t have a good location for one. As far as size, it will be on the frame back near the rear axle, so size is not important.

HYDRODYNAMIC said:
To calculate parking cable force:
Assuming a person can generate full body weight with one leg = 200lbs person = 200lbs at the pedal would be max design force, the average person would push with less than 100lbs to actuate the brakes.
Looks like the F250 pedal is around 2:1 so it can generate 200lbs of pull to engage the brakes
This is confirmed with some of the electric linear actuator brakes systems that are rated at 200 lbs although most actuators are rated to push and not pull so the rating goes down. Some actuators can not handle pull at all so be careful which ones you choose.

Make sure yours is rated at 330 pull and not push. Most actuators are rated push and if you pull too much the bolts for the housing and yokes can break or strip out and then you are rolling down the hill to your death.
Click to expand...

I wanted to calculate that, but I don’t have a F250 pedal to measure. I suspect it’s more than 2:1.

This thing is Chinese junk and I don’t have much faith in it. Actually, it is built much better than the price would indicate. You can look at them on the bay.

In any case, I don’t use the E-brake on a auto trans vehicle. I’m only installing this to satisfy government. It would be nice if it actually worked though. My main concern is switching it on and the motor burn up while it’s fully locked.
 
Actuators can have long strokes same price,
Design it so it pushes the correct force to a lever and use some die springs to limit mechanical stops (bending shit)
.This way you flip it on and off and the actuator travels internal switch stop to internal switch stop and the die springs apply the correct tension.
 
So I rigged up a twin cable test rig. Got a universal E-brake cable kit from Summit. Got a DPDT switch from McMaster and hooked it up on the truck.

C986E658-275A-47A0-BD19-CFE1D5F23C46.jpeg


I jacked the truck up and applied the brake. Both tires were locked. Of course, I’m only turning them by hand, but I think it’s going to work. So I painted the bracket up nice and made some stand off bushings to mount to my frame.

2A715A21-D34E-4F9C-BD0F-F1F98A21D498.jpeg


One issue I have is the kit doesn’t come with any return springs to install at the wheel. There are of course springs on the shoes that pull the cable back when you release it. But the factory cables have springs at the lever also. Not sure if they are needed, but I’m going to locate some.
 
I thought I would update this for those that don’t follow my build. Got some stainless springs from McMaster and installed them at the wheels.

CC2AECA4-BCEF-439E-A562-FAD84C7F59F7.jpeg


Installed the actuator on the frame with some standoffs. It would be nice to just build it on the frame, but I have too much shit running down mine.

3098BD11-C5FB-42CC-9F5E-4F91A4E3084A.jpeg


I tested the brake on this hill. It probably is not steep enough for the Regs, but I think it will lock the wheels no matter what.

712D6369-903E-4E7E-910C-79A356C4FD89.jpeg


So I’m calling this a success. I think I have about $200 in this system. (Not including the axle)
 
Hey before you get too involved in this . This is how a lot of motor homes are but transmission mounted . The one on my RV automatically applies when in park etc .
 
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