Community Forums

BPoland · 02-11-2015, 06:55 PM

To be effective, a breaking system should be proportional, in that the brakes of the toad are applied proportional to how hard the brakes in the coach are applied. Progressive, on the other hand, starts at level the level you have chosen as the start point, and then progressively gets stronger, the longer the brakes are held on.

So is the SMI Stay-In-Play proportional, or progressive? I have heard it stated both ways. If it is progressive, I will look for another solution. If it proportional, Then we have a winner. Also, not sure why it's almost $250 cheaper on RVUpgrades than it is on SMI's web site. :(

mfire1339 · 02-11-2015, 07:12 PM

I've used mine for 6 years and would say it is proportional since I have it set to only brake if I really stab my brake pedal then releases. Hope that helps. I really like it's operation.

Mike

gbburgess · 02-11-2015, 07:18 PM

I believe it is proportional. I have had it or the previous version for at least 10 years and it works great. I recently moved it to my diesel and it works with the tag actuation or the brakes as needed.

smlranger · 02-12-2015, 07:07 PM

According to SMI's website, the Stay-n-Play Duo is 'progressive and proportional'. I am sure you can give them a call and they will answer any questions you have.

We have used their Air Force One for several years and it is an excellent toad braking system.

BPoland · 02-12-2015, 08:50 PM

I tried that. I even reiterated my definition of progressive and proportional, and his response was "You are correct.". It can't be both, unless it is switchable. Proportional is what you need. Old style electric brake controllers were progressive. Hit the brakes and over a predetermined amount of time, the force of the braking pressure will increase regardless of the brake pressure applied in the towing vehicle.
So, proportional is good, progressive, not so much.

Gary RVRoamer · 02-13-2015, 07:47 AM

Your definition of Progressive and Proportional is not universally accepted by brake manufacturers. Not saying you are wrong - just cautioning about what you see in the specs and ads. Take a look at "progressive" in this ad page, for example:
Pro Tow Brake FAQ | D-Brake

One way to be both is to have manual control over the "proportion", meaning you dial in the relative amount of braking on the toad in proportion to the braking of the coach, but the controller "progressively" ramps up from there based on time.

Back in the day, the simplest brake controllers did not have any proportion adjustments - you got a fixed amount of braking whenever the brake was activated. Progressive was a step up from that, allowing it to start low and build up. Adding adjustable brake pressures to a progressive system was another step up, allowing proportional control as a one-time set up thing. Eventually we got to the best systems that automatically change the proportion based on coach braking, but you still need a manual proportion control to balance the relative vehicle weights and your driving preference. And you could still have a progressive control adjustment feature that ramps up the braking under selected conditions. That might be useful in a panic stop situation, where you want maximum braking. Trailer brake controllers usually have both types of adjustments, even though they are basically proportional in normal operation.

BPoland · 02-13-2015, 10:40 AM

Forgive me for being "Thick Headed". Allow me to pose a scenereo, and see if the explains what I am trying to say. You are cruising down Route 95 doing lets just say 65. Up ahead, you see brake lights, lots of them. lets also set some baking efforts. 0 being no brakes, and 10 being Holy $h?t! So, you apply the brakes at level 4 slowing down gradually. The toad, comes on at 4 as well. If you let off the brakes in the coach, all is well, but if you don't let off the brakes and you have a progressive system, after a certain time, even with the coach brakes still at 4, the toad's brakes start ramping up. 5. 6 , 7, 8... as long as your foot is on the brakes, it ramps up. Now you are in a situation where the toad is trying to stop the coach. Not a good place to be. Hard on the toad's brakes and tires.

A true proportional system would apply the toad brakes at 4 (same force as the coach) and will match the braking effort of the coach.

Is that system available. When people say progressive, I am reminded of an early progressive brake controller I was using and looking in my side view mirrors and seeing the smoke off the locked up trailer tires

, because my foot had been slightly on the brakes for about 10 seconds. I didn't like that at all. Went to a Prodigy proportional controller and never looked back.

I'm now trying to decide between a "brake in a box" system, or the built in kind (SMI Stay-In-Play Duo). Maybe what I want isn't available, Or maybe what I'm thinking about being "Progressive" is the way the very old controllers worked.

f14av8r · 02-13-2015, 11:10 AM

The Stay-in-Play Duo cannot be truly proportional since it has no DIRECT way of knowing how hard you are applying the motorhome brakes. It can sense deceleration only and then make a guess about how that deceleration is being generated. The advantage it has over many of the brake-in-a-box solutions it that it cannot operate unless the motorhome brakes are actuated. Most of the brake-in-a-box solutions just sense deceleration, which could be just taking your foot off the gas pedal.

The SMI Air Force One and the Roadmaster BrakeMaster are both truly proportional systems that KNOW the amount of braking force being applied and PROPORTIONALLY apply the toad brakes. The SMI Air Force One system actuates the vacuum booster on the toad brakes so it requires less actual force to the physical pedal in the toad. The Roadmaster Brakemaster uses a larger cylinder that is directly connected to the motorhome braking air system and thus applies a truly proportional force to the toad. Both are excellent systems. The biggest difference is the fact that, with the SMI system you have to modify your toad's brake system. You don't do that with the Roadmaster system.

Both systems are pretty simple on the motorhome side if you have air brakes. If you have hydraulic brakes, the Roadmaster system requires more components since it has to generate it's own air. I don't think the SMI system can be used on a motorhome with hydraulic brakes - only on motorhomes with air brakes.

I'm not sure what SMI means when they say the Stay-N-Play Duo is progressive but their claim that it is proportionally is not quite accurate.

I'd always prefer a truly proportional system over one that isn't.

Selah · 02-13-2015, 11:50 AM

I have the Stay-in-Play and her is my understanding of how they work. If this is not correct someone please let me know. The system is basically proportional in that it uses an accelerometer to determined how much braking force to apply to the toad.
There is a manual setting that sets a base line for the amount of force applied for a specific de acceleration level. Every thing from practically no breaking except for emergency to very hard toad breaking for little deacceleration. Once this is set the system is basically proportional. The greater the deceleration the harder the toad brakes are applied.
In your example of gently applying the coach breaks the deacceleration would be constant and so the toad breaks would remain at that setting and not get progressively applied more. Conversely if you let up on the coach breaks the deacceleration would be less and the toad brakes would lessen.
The caviat is that after a certain amount of time,that the toad breaks are applied they will back off to prevent damage. I don't remember what that time frame was.
Also, when adjusting the initial breaking force you want it light enough that the toad brakes won't be engaged when just using your Lo Jake Brake.

Tiny Dog · 02-13-2015, 04:45 PM

I have the SMI Stay-in-Play in my Jeep wrangler that I tow with a gas motorhome. I think that it operates both proportionally and progressively. On a easy stop if you keep your foot on the brake as you roll along you can feel the Jeep slowly braking harder. If you stop like a deer ran in front it applies the Jeep brakes very hard. It seems to be the best combination of both systems.

BPoland · 02-14-2015, 04:55 AM

It now makes sense to me, why some people like to have a higher breaking force required before the Stay-in-Play activates. For light stopping power, it's probably not needed. Only for coming down from highway speeds and hard stops.

Thanks for the responses! I'm pretty sure that a Duo will be in my Cherokee soon.

f14av8r · 02-14-2015, 05:03 AM

Quote:

Originally Posted by Selah

I have the Stay-in-Play and her is my understanding of how they work. If this is not correct someone please let me know. The system is basically proportional in that it uses an accelerometer to determined how much braking force to apply to the toad.
There is a manual setting that sets a base line for the amount of force applied for a specific de acceleration level. Every thing from practically no breaking except for emergency to very hard toad breaking for little deacceleration. Once this is set the system is basically proportional. The greater the deceleration the harder the toad brakes are applied.
In your example of gently applying the coach breaks the deacceleration would be constant and so the toad breaks would remain at that setting and not get progressively applied more. Conversely if you let up on the coach breaks the deacceleration would be less and the toad brakes would lessen.
The caviat is that after a certain amount of time,that the toad breaks are applied they will back off to prevent damage. I don't remember what that time frame was.
Also, when adjusting the initial breaking force you want it light enough that the toad brakes won't be engaged when just using your Lo Jake Brake.

This is the biggest problem I have with a lot of the braking systems out there. Most deceleration sensing systems will engage the toad brakes when you are just using your engine brakes. That's the last thing I want. I only want the toad brakes applied when my coach brakes are applied.

As others have stated, the better deceleration sensing systems allow you to set the onset level to eliminate braking on the toad with either light braking on the motorhome or just deceleration. Better still though are the systems that only apply the toad brakes when the motorhome brakes are applied and then apply them proportionally.