Surge Brake Explanation Needed

[mrmamiller]

I need some explanation of surge brake systems. A friend is buying a 22ft boat/trailer. The trailer is a tandem axle trailer and has surge disc brakes. I believe the trailer is in the 5500# range. The present owner has said something about a resistor that can be changed depending upon the amount of "braking", not sure if this is braking going forward or lack of braking when backing up. I am not familiar enough with surge brake systems to understand how a resistor comes into play, sounds like something electrical might happen when going into reverse, not sure. Can someone shed light on what may be going on? Or, is the present owner not explaining things adequately (I wondered if "resistor" got confused with "restrictor", as in an orifice).

 

[smokeonthewater]

Re: Surge Brake Explanation Needed

there are NO resistors in surge brakes..... we can't read his mind but he MAY have been talking about the shocks in some of them

there is a back up solenoid on some also that blocks the flow of brake fluid when it is energized by the back up light circuit but there is no adjustment on those... they are imply on or off

 

[H20Rat]

Re: Surge Brake Explanation Needed

So to add to what smoke said, here is the 1 minute version of surge brakes. Think of your brake pedal in your car. To slow down, you push on it, which applies hydraulic pressure to the brakes. In a surge brake system, that pedal is the tongue of the trailer, and the hitch ball becomes your foot. When the vehicle slows down, the ball pushes on the trailer tongue, which in turn pushes hydraulic fluid into the trailer brakes.

Anyway, at no point in the braking cycle (of the vehicle or the trailer!) does any electricity come into play...

 

[tpenfield]

Re: Surge Brake Explanation Needed

So to add to what smoke said, here is the 1 minute version of surge brakes. Think of your brake pedal in your car. To slow down, you push on it, which applies hydraulic pressure to the brakes. In a surge brake system, that pedal is the tongue of the trailer, and the hitch ball becomes your foot. When the vehicle slows down, the ball pushes on the trailer tongue, which in turn pushes hydraulic fluid into the trailer brakes.
Anyway, at no point in the braking cycle (of the vehicle or the trailer!) does any electricity come into play...

I like that explanation . . . I usually think of surge brake systems as wanting to keep the trailer the same distance from the tow vehicle. So as the tow vehicle slows down, the surge brake actuator applies the brakes on the trailer. If the tow vehicle slows down quickly, the surge brake actuator applies the brakes harder.

nothing about a resistor involved. Perhaps that person was referring to the electrical lock out for backing up. Those are needed for disc brakes and work off of the backup light of the tow vehicle.

i had surge disc brakes on my tandem trailer for my 24 footer . . .about 6500 lbs total load. They worked well.

 

[GA_Boater]

Re: Surge Brake Explanation Needed

I'm wondering if there is some confusion here. Is the term surge brake being used generically for either electric brakes or electric over hydraulic brakes? Those are the only two that use electric power other that the previously mentioned backup solenoid, which is only on or off with no adjustment.

 

[agallant80]

Re: Surge Brake Explanation Needed

Is there an easy way to tell if its surge or electric? Wouldn't surge have 4 or 5 flat and electric have round 7 connector?

 

[GA_Boater]

Re: Surge Brake Explanation Needed

Is there an easy way to tell if its surge or electric? Wouldn't surge have 4 or 5 flat and electric have round 7 connector?

I don't think it could be much easier. Also the tow vehicle will need a brake controller of some type connected to the matching connector on the vehicle side.

 

[Splat]

Re: Surge Brake Explanation Needed

They may have been talking about a proportioning valve. Common on hydraulic brake systems, tho not common on boat trailers, I've encountered some equipment trailers that had adjustable ones.

 

[SolingSailor]

Re: Surge Brake Explanation Needed

The last time I bought a new coupler / master cylinder assembly, I had to specify whether for drum or disk brakes.
I believe the outlet orifice is different, but not sure how. Is this the subject of the OP's question? And can anyone clarify this issue?

 

[tpenfield]

Re: Surge Brake Explanation Needed

The last time I bought a new coupler / master cylinder assembly, I had to specify whether for drum or disk brakes.
I believe the outlet orifice is different, but not sure how. Is this the subject of the OP's question? And can anyone clarify this issue?

Surge brake master cylinders for drum brakes have a check valve installed. Disc brakes do not (and can not ) have a check valve at the master cylinder.

 

[H20Rat]

Re: Surge Brake Explanation Needed

The last time I bought a new coupler / master cylinder assembly, I had to specify whether for drum or disk brakes.
I believe the outlet orifice is different, but not sure how. Is this the subject of the OP's question? And can anyone clarify this issue?

drums often do not need a reverse lockout, they don't have much braking force in reverse.

 

[bruceb58]

Re: Surge Brake Explanation Needed

Surge brake master cylinders for drum brakes have a check valve installed. Disc brakes do not (and can not ) have a check valve at the master cylinder.

Just to add what Tpenfield said...Purpose of the check valve, which is often called a residual valve, leaves the line going to the drum brakes slightly pressurized. This allows the drum brakes to activate faster.

With disc brakes, this extra pressure would cause the brakes to drag and overheat.

 

[mrmamiller]

Re: Surge Brake Explanation Needed

Hi, OP here. My original question has to do with where or why there would be a resistor that can be changed based on weight of trailer. The rest of surge brakes I understand.

 

[GA_Boater]

Re: Surge Brake Explanation Needed

The only possible thing is the brakes are not hydraulic surge brakes. Do you have any more info?

 

[bruceb58]

Re: Surge Brake Explanation Needed

The "restrictor" he was likely talking about was the reverse solenoid that prevents the disk brakes from operating in reverse. This is normal with disk brakes.

Blocking Solenoid (Td 11250) - Champion Trailers

 

[alldodge]

Re: Surge Brake Explanation Needed

Hi, OP here. My original question has to do with where or why there would be a resistor that can be changed based on weight of trailer. The rest of surge brakes I understand.

Answer: Surge brakes do not use a resistor of any kind

Have never heard of any brake system which uses a replaceable resistor. We need more information in order to answer your question. If you have some other kind of brake system please provide more info, pictures, diagrams, something

 

[bruceb58]

Re: Surge Brake Explanation Needed

He says this in his first post:

The trailer is a tandem axle trailer and has surge disc brakes.

I think he heard resistor when it really was something else.

 

[GA_Boater]

Re: Surge Brake Explanation Needed

Hi, OP here. My original question has to do with where or why there would be a resistor that can be changed based on weight of trailer. The rest of surge brakes I understand.

No, there is no resistor unless the brakes are electric. The "resistor" would be the brake controller which allows the driver to change the brake bias depending on weight or road conditions.

 

[mrmamiller]

Re: Surge Brake Explanation Needed

I'll know more when the friend's boat/trailer arrives in a month.