Friction trailer brakes

[Rod]

I am thinking about putting a friction brake setup on a wagon gear for people hauling. This is not my first attempt at doing this, the last being not as successful as I want in terms of braking power. On that attempt I rigged two brake shoes that pressed against the tires on the rear wheels of a cart that I actuated with a peddle, cable and foot operator. The mechanism worked fine and I had decent leverage but the friction between the rubber tire tread and the steel brake surface was not enough to be very effective. I also tried a wooden brake pad which was not any better.
I know this is done with steel surface wheels and I am interested in how to make it work reliably and with good braking effect on rubber auto type tires. Any suggestions or actual experiences are welcome. Thanks.

[jac]

Hi Rod.. Are the rubber tyres off an automobile ? can the drum brakes not be added to the axle.. if not, then perhaps a chunk of car tyre could be used instead of the wood….
John

[Andy Carson]

I think that standard drum brakes or standard wagon hydraulic type braking system would be your most practical bet…

If you are interested in something more inventive, I have thought in the past about using using an auto differential and some additional gearing to attach the “driveline” to a torque converter which is fixed solidly on one end to the frame of the wagon. You would have to play with the gearing a little to make it work, but in theory, you could end up with a system where the torque converter begins to lock up when the downhill speed exceeds the lockup rpm and is minimally engaged when the speed is below this the lockup rpm. You would probably still want to disengage the brakes when on the flat, but when they are engaged, you would have self feathering brakes preset to a specific downhill speed. It could be pretty cool! It never made it off the drawing board for me, but I think the concept makes sense in theory and might be very useful for someone who uses wagons more than I do.

[Rod]

I have this idea which I am going to experiment with. Basically its using a boat trailer winch (which I have) to add leverage to the friction brake system. And I am going to try some pieces of rubber tire tread bolted to my brake shoes to increase friction against the trailer tires.
The plan is to mount the winch on the side of the seat where I can move the lever with my right hand. The brakes are moved against the tire now with a cable and lever setup. By using the winch I will have a ratchet lock in either direction and a free travel position. Because it will have a much better mechanical advantage than the existing pedal setup I should be able to really put some good pressure on the brake pads. The way I envision it the brake pedal which I now use can still be functional but the winch will provide an override for those steep hills and heavier loads. I will let you know how it works out.

[mitchmaine]

@Rod 21816 wrote:

I have this idea which I am going to experiment with. Basically its using a boat trailer winch (which I have) to add leverage to the friction brake system. And I am going to try some pieces of rubber tire tread bolted to my brake shoes to increase friction against the trailer tires.
The plan is to mount the winch on the side of the seat where I can move the lever with my right hand. The brakes are moved against the tire now with a cable and lever setup. By using the winch I will have a ratchet lock in either direction and a free travel position. Because it will have a much better mechanical advantage than the existing pedal setup I should be able to really put some good pressure on the brake pads. The way I envision it the brake pedal which I now use can still be functional but the winch will provide an override for those steep hills and heavier loads. I will let you know how it works out.

hey rod, i like your idea. about the brake pads though, i thought i might add that the coefficient of friction with rubber to rubber is emense. i tried it once on a cart and if you were stopped no way could those wheels spin. but if you had a little speed up, and not much, when you touched the brakes it tore every thing to peices. it was just a t-bar running under the wagon frame coming up against the front of the wheels made of 1″ square tubing in a little frame. probably underbuilt. anyway, that was my experience, take it for what its worth. don’t give up as easy as i did and good luck with your project. mitch

[Rod]

That’s great to know, about the friction rubber to rubber that is. I thought it might be good but have never tried it. Thanks.

[mstacy]

Rod,

Is your primary intent to use this as a parking brake or to control speed on long descents? I would be concerned about using a pneumatic tire as the friction medium for the latter.

Ultimately all friction brakes convert kinetic energy to thermal energy.

But if you really just want a parking brake consider mounting the brake pad on a lever oriented such that when the animals pull forward it tends to engage harder. This would be self energizing … i.e. power brakes on the cheap. However that self energizing feature only works in one direction.

Regards,

Matt

[Andy Carson]

Rod,
I have a loosely related story that might help. I used to use a razor scooter as part of my ride to work (insert joke if you must…). The brakes on these things are a simple hinged metal pedal that you press down on with your foot pushing it onto the plastic rear wheel, creating resistance and some braking effect. Kinda sounds like what you are proposing, with a different mechanism and scale. The metal/plastic interface didn’t create a very strong braking action for moderate hills unless I put nearly all my weight on top of the flap. If metal on plastic isn’t that great for braking, I could believe that metal on rubber isn’t that great either… The biggest problem with these brakes was that if it was raining or if the wheels got dirty, the water/dirt acted as a lube between the wheels and the pedal and the brakes stopped working completely (as opposed to just poorly). The other problem was (as Matt mentions) the peddle gets really hot. It burnt the bottom of one pair of shoes and pretty quickly wore a hole through the metal pedal. This actually turned out to be a good thing, more or less, because with a big wear hole in the pedal, the plastic wheel actually started to rub on the sole of my shoe, with the result being improved braking, especially when it was wet or if the wheels were dirty. So, I think that your rubber on rubber idea might be great in the short term. Over the long term (as on a longer hill), the rubber on the soles of my shoes has melted though (and ruined a couple pairs of shoes), which could also happen to your wheel/rubber combo and could be bad bad… Interestingly, the friction coefficient of brake materials on cast iron is only 0.4 (compared to coefficients of 0.8 or so for tires on concrete). I bet from a brake design point of view, the friction coefficient is not actually very important (as this can be overcome with leverage) but the ability of the materials to resist heat is the primary design consideration. Just so you know, even with the hole in the pedal on the scooter, I still had to put alot of weight on the rear wheel and keep the speed down in order to maintain a controlled decent on a hill. Rim mounted brakes on a bicycle have at least 4 times more braking power (with less effort due to the machnical advantage) with the same weight, even though they use a rubber/metal interface. I bet you will get the most bang for your buck by using the winch to gain some mechanical advantage, but I bet you are still going to have to crank pretty hard. I know these aren’t really the same situation, but I hope this helps a little…

[Rod]

Thanks for the thoughtful comments, they keep the wheels turning (in my head). My latest thought is to construct a laminated rubber and wood brake shoe. The wood would take most of the friction (bigger surface) and the rubber would be their to add friction. This can be done (I think) by cross bolting the materials together and attaching them to my steel shoe.
The comments on friction and heat are good. In my case however the hills are not that long and I do not need to drag the brakes, even locking the back wheels would work as I could have my mule drag the wagon down the hill which is gravel, no pavement.

[TBigLug]

I know I’m digging in old threads again (shocker lol) but an ida I threw around the old brain cavity last year was using an axle off a equipmen trailer with an electric brake setup and molunting a single deep cycle battery under the driver’s seat and a trailer brake controller on the floor (simple push button switch in floor to activate controller). That way the braking power can be adjusted for the “load” so to speak and the floor of the trailer could be loer for the elerly to get on without climbing too many steps. Just another thought.

[Rod]

@TBigLug 27606 wrote:

I know I’m digging in old threads again (shocker lol) but an ida I threw around the old brain cavity last year was using an axle off a equipmen trailer with an electric brake setup and molunting a single deep cycle battery under the driver’s seat and a trailer brake controller on the floor (simple push button switch in floor to activate controller). That way the braking power can be adjusted for the “load” so to speak and the floor of the trailer could be loer for the elerly to get on without climbing too many steps. Just another thought.

The brake controllers that I have used are automatically activated by inertia. They apply current to the magnets in proportion to the stopping velocity of the vehicle and that stopping velocity is varied by the work of the truck brakes. I am not sure how well this would work with horses applying the speed reduction force required to activate the inertia mechanism in the controller. They all have a manual override which should work fine but may be hard to apply in a graduated manner while driving the team. Something to think about.

[TBigLug]

I see you have the fancy bake controllers! lol I use the time delay instead of the motion sensing (ie. inertia operated) on all my trucks because they were cheaper.

http://www.ehow.com/list_7484008_types-electric-brake-controllers.html

TSC carries them for about $50 or they can be fond online for around $20 used. You can set the delay to gradually apply the brakes (1-10 secs or so) so it’s not quite a jarring stop.

[Carl Russell]

I will not add to the discussion about brake design or materials, but I will say that I think you will get much better results if you put your brakes on the front wheels of the wagon. Brakes on the rear wheels are holding back a load that is already downhill from them, so the weight is not adding the to friction component. If you brake the front wheels you get the added weight of the load on the wheel itself which increases the friction and therefore the braking capacity.

Carl

[Big Horses]

Carl’s exactly right… from riding “choppers” (where you’d remove the front brake) you find that about 70% of your braking power comes from the weight transfer to the front axel on a vehicle…. same goes to anything moving. More than once, I’ve slid that back wheel through an intersection, with very little effect noticed!:eek:
I’d bet you’ll have plenty of friction with just a wood block, but one thing to think about…. one of the best friction reduction agents on rubber is water….. when we press rubber bushings into truck suspensions with a 100 ton press, we don’t use oil…we use water, as it works better….. just some food for thought…. keep those “brain wheels” turning!
John

[Author]

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