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You should check the specific legal requirements with the Dept of Motor Vehicles in the area you expect to do your towing.
If the trailer has an electric brake system, the emergency breakaway regulations require that the trailer be provided with an emergency battery backup system, that will provide electrical power to the brake magnets during the trailer break away brake activation process. In an electric_breakaway system, there is a breakaway switch with a pull pin and cable which, when attached to the tow vehicle, will provide electrical activation of the trailer brakes if the trailer disconnects from the tow vehicle during highway travel. The components for this system are normally packaged as an Emergency Breakaway Kit which has battery and charger, emergency switch and battery case in one package.
Hydraulic surge brakes are a totally trailer self-contained braking system, requiring no electrical, hydraulic or other connection of brake sensing components to the tow vehicle for automatic operation of the trailer brakes. In a hydraulic surge brake system, the inertial differential pressure developed between the tow vehicle and the trailer, during the braking process, creates a mechanical pressure which is applied to the push rod of the master cylinder in the hydraulic surge brake coupler. This mechanical pressure is proportional to the difference in pressure between the two vehicles and therefore, the hydraulic output of the brake coupler, and resulting brake operation, is automatic, regulated, and proportional to the amount of braking being applied to the tow vehicle.
Simple, effective and a proven performer on tens of thousands of trailers, this brake system has been the braking package of choice for most boat trailer owners for decades. The vast majority of boat trailer hydraulic surge brake systems are package with drum brakes, however they can be used with disc brakes with equal effectiveness. Both systems, however, have their own unique design, installation, and maintenance considerations.
Trailer hydraulic drum brake systems
can be installed on a wide variety of axle capacities.
These are the axle capacities used on most boat, utility, and RV trailer applications.
Certain drum brake sizes are available as either
Hydraulic drum brakes are also available as either Standard or Free backing Brakes.
The hydraulic surge brake coupler does an excellent job of providing automatic proportional braking response to tow vehicle braking while towing. However, it cannot distinguish between (braking while towing) and the mechanical differential pressure created between the tow vehicle and trailer while backing up. Consequently, standard (uniservo) drum brakes, which can retain 20% or more of their braking capacity while backing up, normally require a method of deactivating the brakes while backing up. This is normally done with a reversing solenoid kit.
solenoid is activated when the backup lights on the tow vehicle come on. At
this time, all hydraulic pressure in the brake system is released as any hydraulic
out put from the master cylinder is dumped back to the master cylinder reservoir.
When the back up light signal is removed, the solenoid is deactivated and the
surge brake system reverts back to normal operation.
WARNING!! Never mechanically pin out the brake coupler!! This could lead to a non operating brake system if you forget to remove the lock out pin.
Free backing Brakes, on the other hand, automatically disengage while backing up. The reverse rotation of the wheel triggers activation of components internal to the individual brake clusters that deactivates the brakes while backing up. The brakes then re-engage for normal operation when the wheel turns forward. This is why Free Backing Brakes are normally the brakes of choice in a hydraulic drum brake system. To combat corrosion, these brake clusters are now available with hot dip galvanized backing plates, stainless steel brake springs, and can easily be fitted with a freshwater washdown kit to purge salt and dirt from the brake interior.
Click here for information on TROUBLE SHOOTING HYDRAULIC SURGE BRAKES
The primary difference in their operation is that hydraulic drum brakes can be manufactured with free backing components integral to the brake cluster for automatic deactivation of the brakes as the trailer backs up. Disc brakes cannot. Disc brakes require the installation of the free backing solenoid kit to deactivate the trailer brakes while backing up. In disc brake systems, it may also be necessary to remove the hydraulic return flow restrictions present in most brake couplers.
In a drum brake system, the shoe return spring pulls the wheel cylinder push rod in and the master cylinder return spring also pulls, providing a strong differential pressure, for the return of brake fluid from the wheel cylinder back to the master cylinder upon release of braking pressure from the master cylinder push rod. However, in a disc brake system, only the master cylinder return spring provides a pull return for brake fluid when the brakes are released.
For this reason, it is essential that all check valve, and other restrictions that would inhibit the return flow of fluid back to the master cylinder, be removed. If they are left in place, the brake calipers can remain locked or dragging, and may not allow the brakes to release as you attempt to pull forward.
WARNING!! It would be advisable to get written approval from the manufacturer of any brake coupler that you propose to do these mechanical alterations on. To make alterations to the interior components of the brake coupler without such approval would probably VOID any warranty or product liability responsibilities that the brake coupler manufacturer might have. It would be recommended that if you intend to install disc brakes, purchase a brake coupler designed specifically for that application.
Painted automotive grade brake springs rot, adhesively bonded shoe pads become detached from their foundation plates, and water soaked magnet electrical insulation commonly fails. For this reason, most boat trailer owners opt for hydraulic surge brakes either disc or drum.
Electric brakes, as with hydraulic drum brakes, are available to fit a wide variety of axle capacities.
(CAUTION) It should be noted that electric brake hub drums must have a flat machined magnet contact surface to operate successfully with electric brakes. Some hub drums are available in a hydraulic only style without this smooth machined surface. Hydraulic only style drums MUST be avoided when electric brakes are used.
Electric style drums can be used on either electric or hydraulic systems, but hydraulic style drums can only be used on hydraulic brakes.
Electric brakes require a brake controller to apply power to the brake system. With electric brakes, as power is applied to the electromagnets in the brake cluster, the magnets are pulled to the interior flat surface of the hub drum. As the wheel and drum turn during highway travel, this attraction of the magnet to the flat drum face pulls the lever arm of the brake actuating cam, rotating the cam and forcing the brake shoes out to contact the drum braking surface. The more power applied to the magnets the greater the leverage on the came resulting in greater braking response.
Most electric brake controllers are dash mounted allowing the driver access to the manual override button. The manual override button allows the driver to activate the trailer brakes without operating the tow vehicle braking system. This can be important if your trailer is prone to sway. By bumping the electric brakes on the trailer during sway, the driver can dampen and control sway problems should they occur.
One negative feature of electric brakes is that if you use a dash mounted brake controller, you must have a controller on every vehicle that you tow the electric brake equipped trailer with.
These controllers are dash mounted
and have a simple adjustment that allows the driver to adjust the brake power
output dependent upon the load on the trailer. For example, a flatbed equipment
trailer is being towed with nothing on the trailer bed and the trailer brakes
are locking up. The driver moves the adjustment bar down to a point just below
where the brakes lock up. This is the proper controller set point for that
load. Later he loads a tractor onto the trailer and readjusts power upward
to a point just short of brake lockup. If a travel trailer is the towed load,
the adjustment need only be made one time. These controllers apply current
to the magnets in a power ramp cycle. Some controllers have this time ramp
preprogrammed, other controllers allow a user adjustment of the time cycle.
This controller is not position sensitive and can be mounted at any angle.
This is the simplest and most economical controller
and many times works better than other types.
These controllers normally contain an inertial mass attached to a pendulum. As the tow vehicle brakes, the inertial mass swings the pendulum forward, providing a variable electrical output to the brake magnets and therefore providing a variable trailer braking response. These controllers are position sensitive and must be either mounted level or the inertial mass device must be compensated for non-level installation. This is done by means of the sensor adjust control.
Power gain adjustments are
also available on these controllers to compensate for varying load conditions,
and they also contain the manual bypass button discussed earlier.
It is important to note that this
controller must be positioned so that the inertial mass sensor will swing
forward during tow vehicle braking. Also, the tow vehicle driver does not
have manual over ride capability with this style unit.
This controller is connected into the brake line tubing of the tow vehicle and has a pressure sensor that determines what level of braking is being applied to tow vehicle brakes. It then sends a proportional electrical power out put to the trailer brake magnets The pressure sensor on this type of controller requires a small amount of brake fluid from the tow vehicle brake system.
CAUTION: Before installing this type of brake controller, confer with the tow vehicle manufacturer to determine whether this is allowable. Altering tow vehicle brake systems may void warranty and product liability responsibilities.
As previously mentioned, all trailers requiring brakes are required by D.O.T. safety regulations to be equipped with an emergency breakaway brake activation system. On trailers equipped with electric brakes, this is achieved with a breakaway switch and a trailer mounted emergency power battery. If the trailer disconnects from the tow vehicle during highway travel, the pull pin on the breakaway switch activates the trailer brake magnets providing braking power from the emergency battery as the trailer stops.
Electric brake controllers should be provided with internal reverse voltage protection to protect the controller in case the emergency breakaway switch is activated while the system is still connected to the tow vehicle brake controller. However, caution should be exercised to assure correct electrical connection of all system components. The brake controller can be damaged or destroyed by improper wiring connections.
Be sure to install an automatic reset circuit breaker in the power cable from the battery to the electric brake controller.
Remember, each brake magnet will draw about 3 amps during full power operation, therefore:
Brake magnets should be parallel wired for optimum system performance.
Also never use the trailer frame or brake cluster backing plate for the (-) brake negative current return. The negative (-) wire must be brought all the way through the trailer plug back to the tow vehicle negative for optimum system performance. Loose connections at the trailer plug, wire taps, and voltage drop from wiring that is too small can radically affect your electric brake system performance. Installation tip - Never use pinch type wire taps for electric brake wiring. They may be adequate for trailer lighting systems, but the high current draw for electric brakes require compression (crimpon) connectors or soldered wire taps for best performance
Hydraulic surge brakes are a totally trailer self contained braking system, and therefore all trouble shooting analysis can be concentrated on the trailer to resolve braking problems. However, with electric brakes, both the trailer and tow vehicle contain components integral to the overall electric brake package and therefore trouble shooting the electric brake system can be more complex.
The mechanical operation of electric brakes is fairly simple, if power is available to the magnets, and the magnets are functional. Therefore, we will assume that mechanical problems such as
The majority of problems that occur with electric brakes can be traced to an electrical system problem, and we will concentrate our attention there.
A 12 VDC VOLTAGE TESTER, VOLTMETER, OR TEST LIGHT PIGTAIL WILL BE NEEDED FOR ELECTRICAL SYSTEM TEST.
First, it is essential to isolate the problem area.
(Answer) Unplug the trailer from the tow vehicle and use a 12 VDC battery with a fuse or circuit breaker, for short circuit protection, to apply full 12 VDC to the pins of the trailer connector connected to the wires going to the wheel magnets. As you connect the 12 VDC source, you should hear a notable click as the magnets are energized and pulled to the flat drum surface. Another method of testing brake magnet operation is to place a compass near the hubdrum.
If, for example, you had brakes on both axles of a tandem trailer, you should go to each hub drum and assure that each brake cluster magnet is operating. If you could hear brake magnet activation on 1 axle and not the other, you may well have a bad wiring connection on the trailer wiring harness.
Conversely, you may hear 3 magnets click but not # 4. Closer inspection may indicate a bad magnet or a bad wire connection at that magnet.
CAUTION: If a short circuit exists in the trailer electrical system, you could receive burns from melting electrical components if you do not use a fuse or circuit breaker for over current protection when connecting the test battery.
If all magnets click aggressively, the trailer electrical system should be in order, if the wire size is large enough to handle voltage drop. NOTE: Be sure that the brake magnet (-) negative wire is the same size as the positive (+) wire and be sure not to connect the negative (-) return wire to the brake backing plate or trailer frame.
The negative must return thru the trailer plug and connect to the tow vehicle negative for optimum system performance. It is also essential that brakes be PARALLEL WIRED not series wired.
Dash mounted brake controllers, both inertial deceleration type, and power adjust only type, are the controllers most commonly used. They both take brake light (on) sensing signal as the primary control input and if this input is positive (on), the power amplifier in the controller is biased (turned on), at which time, depending on power adjust set point, and/or brake sensing pendulum position, a proportional amplifier power output is sent to the brake magnets.
To test output from the controller, use a voltmeter reading 12VDC at mid scale. Some controllers will not give satisfactory readings with an RMS voltmeter and you will need to use a standard 12 volt bulb pigtail for test.
Testing Battery Input
First test your battery power INPUT tap at the brake controller to assure that you have full 12VDC thru your auto reset circuit breaker and up to the controller.
Testing Manual Over-ride
At the power output tap of the brake controller, connect your voltmeter and operate the MANUAL BYPASS BUTTON on the controller. You should develop full output voltage within 3 or 4 seconds. If you have output voltage here and your brake magnets are not picking up, you should find a loose connection between this point and the previously tested trailer as a problem.
Testing Automatic Operations
On inertial deceleration controllers, set the gain control to it's maximum (aggressive) position, and with power adjust controllers set the output to maximum.
Now with your voltmeter connected to the same power output tap we tested earlier, push the brake pedal down and operate the tow vehicle brake lights. Power output voltage should go to maximum. If it does not, check to be sure that brake light sensing voltage is available at the proper tap of the brake controller.
If you have battery input power available, and you have brake light sensing signal available, but you have no output power, the problem should be internal to the controller and will require repair (contact the manufacturer for recommendations) or replacement.
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