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Review of Demco Brake Actuator - Surge Brake Actuator - DM8759411

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Demco Brake Actuator - Surge Brake Actuator - DM8759411 Review


Jeff: Hello, everybody. This is Jeff at etrailer.com. Today, we're going to take a look at this Demco hydraulic drum brake actuator with the four inch drop. It's got a two and five 16ths diameter ball, has an 8,000 pound weight capacity.Now this hydraulic actuator will activate your trailer's brakes when your tow vehicle slows or stops. Basically, what happens is when you apply the brakes in your tow vehicle, deceleration occurs, and the momentum will push your trailer toward the rear of your vehicle. So with a surge brake system, the actuator is triggered as your trailer moves forward once the tow vehicle starts to slow down.And when this happens is the inner portion of the actuator right here will contract in and applies force to the master cylinder, which in turn supplies the necessary hydraulic pressure to engage your trailer's brakes.

Now, right around here, where the inner slide goes into the outer portion, they do use an acid talc co-polymer lining. And that provides a nice, smooth operation as the actuator telescopes in and out.They do use this easy latch coupler mechanism for a nice simple, secure hookup and disconnect. This will let you hook up when the latch is in the closed position like it is now. All you have to do is drop the coupler over the hitch ball and the latch will snap into place.I want to demonstrate that as I happen to pull a two and five 16 standard ball that this coupler fits on. And you can see with it in the lock position.

If you go up over your ball and then you just push down. You see that it automatically latches and then it locks into place, and you're ready to tow.So you don't have to move any of the latch around. The only time you have to move the latch is when you run to remove it from the ball. Just pull up on your trigger, pull up the handle all the way. And then that'll allow you to remove it from the ball, so it's pretty simple.

And just close your latch and you're ready to go hook up again.Now this coupler does offer a four-inch drop, which will help you match the tow vehicle height. It is a heavy duty steel construction. You can see it has a nice zinc plating that offers a 200 hour salt spray rating for corrosion resistance. Now we mentioned the master cylinder that's in the back here.This composite master cylinder is durable and efficient. It's a glass reinforced nylon construction.

So it resists rust and corrosion. And it's a very large reservoir. So it provides increased capacity for the brake fluid. And if you notice on the top here, it uses the automotive style diaphragm cap, which creates a completely enclosed system to help prevent contamination of the brake fluid.Now it does come with this breakaway cable and latch hook. It is all included. And it is required by law to have a breakaway cable. What this does is prevents a trailer runaway situation. So what you'll do is take your latch hook right here, hook it to your tow vehicle. And then this cable runs to a lever right here.So what happens is, if your trailer happens to come detached from your tow vehicle, it'll pull on this cable, which will activate the lever, which will activate the master cylinder to apply pressure to the brakes to stop it. So it helps prevent a runaway situation if your trailer disconnects from your tow vehicle.Now it is a bolt-on installation. If you see here on the bottom, it has the spots in the holes for installing. Does require a half inch by four and a half inch long grade five bolts for mounting. And those are not included. This part is made in the USA.Few specs again. This is for trailers with hydraulic drum brakes. The ball size it fits is a two and five 16ths diameter. Gross towing weight capacity is 8,000 pounds. Maximum towing weight capacity is 800 pounds. It is designed to mount on a straight, three inch wide trailer tongue. And this actually also goes by the model number DA91.One last note I do want to mention on this. Because this actuator does not include a reverse lockout, it is recommended that you equip your trailer with either a reverse lockout solenoid that installs right in the back of the master cylinder here, or a free backing brakes on your trailer so that you can drive in reverse without the actuator triggering your trailer's brakes.But that should do it for the review on this Demco hydraulic drum brake actuator with the four-inch drop for a two and five 16ths diameter ball. And it has an 8,000 pound weight capacity.


Info for this part was:

Employee Jeff D
Installed by:
Jeff D

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