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Hydrastar Vented Marine Electric Over Hydraulic Actuator for Drum Brakes - 1,200 psi

Hydrastar Vented Marine Electric Over Hydraulic Actuator for Drum Brakes - 1,200 psi

Item # HS381-8066
Our Price: $846.11
Brake Actuator
Shipping Weight: 12 lbs
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Anodized aluminum electric-hydraulic actuator lets you use your brake controller (sold separately) to activate your trailer's hydraulic brakes. Includes rust-resistant marine-grade gasket and stainless steel hardware. Vented plate releases heat. 1-800-940-8924 to order Hydrastar brake actuator part number HS381-8066 or order online at Free expert support on all Hydrastar products. Great prices and Fastest Shipping for Hydrastar Vented Marine Electric Over Hydraulic Actuator for Drum Brakes - 1,200 psi. Brake Actuator reviews from real customers.
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Hydrastar Brake Actuator - HS381-8066

  • Electric-Hydraulic Brake Actuator
  • Drum Brakes
  • Hydrastar
  • 1200 psi

Anodized aluminum electric-hydraulic actuator lets you use your brake controller (sold separately) to activate your trailer's hydraulic brakes. Includes rust-resistant marine-grade gasket and stainless steel hardware. Vented plate releases heat.


  • Electric-over-hydraulic brake actuator activates your trailer's hydraulic brakes when you apply the brakes in your tow vehicle
    • Brake controller (sold separately) is required to send signal from tow vehicle to actuator when brakes are applied
    • 7-Way trailer connector (sold separately) is needed to transmit signal from brake controller
  • Improved functionality when compared with surge brake couplers
    • Faster response time - trailer brakes are triggered when you apply brakes in tow vehicle, as opposed to when trailer pushes against hitch ball
    • No need to manually lock out brakes when you back up
    • Trailer brakes can be intentionally activated when you reverse
    • Manual override on brake controller can be activated so you can engage the trailer brakes without having to apply your vehicle brakes
  • Vented end plate releases pressure, moisture, and heat in order to protect the internal components
    • Allows actuator to be mounted in places where most actuators would overheat
  • Electronic, proportional pressure valve ensures that braking is smooth and effective
  • Built-in bleeder screw lets you easily flush air out of the brake lines
  • Durable extruded aluminum provides superior corrosion resistance
    • Marine-grade gasket and stainless steel hardware make this ideal for marine use
  • Compatible with any standard, 5-amp-hour-battery breakaway kit (sold separately)
  • DOT compliant
  • Unit installs on trailer frame and connects to trailer's wiring and hydraulic brake lines (sold separately)
  • Made in the USA


  • Application: single-, tandem-, or triple-axle trailers (8,000 lbs or larger) with drum brakes
  • Maximum output pressure: 1,200 psi
  • Hydraulic port size: 3/16"
  • Power: 12V DC
  • Dimensions: 11-3/4" long x 3" wide x 7-3/8" tall
  • Wire configuration:
    • Black: 12-volt power
    • Blue: brake controller
    • Yellow: breakaway
    • White: ground
  • 2-Year limited warranty

Note: Do not power wash the Hydrastar actuator or take it through a commercial car wash. High-pressure water may damage the seals on the actuator.

The Hydrastar electric-over-hydraulic trailer brake actuator applies pressure to your trailer's hydraulic brake system in response to the electrical signals sent from your in-cab brake controller. As a result, your trailer's hydraulic brakes will be activated every time you apply the brakes in your vehicle or press the manual override on your controller. This setup is ideal for boat trailers because you will get responsive hydraulic braking, which you control conveniently from inside your vehicle with your electric brake controller.

Hydrastar Electric-Over-Hydraulic Actuator vs. Standard Surge Brake Actuators

With the Hydrastar electric-over-hydraulic actuator, you can get all the benefits of towing with an electric brake controller while using hydraulic brakes. Because this actuator will activate according to the settings you have chosen for your brake controller (sold separately), you will have more control over when and how your trailer brakes engage. Depending on the features of your brake controller, you may be able to control both the rate and intensity with which your trailer's brakes activate. You can also use the manual override on your brake controller, which allows you to engage the trailer brakes without having to apply the brakes in your vehicle. And perhaps most impressive, if you have a proportional brake controller, your brakes will be activated with an intensity that matches the braking speed and power of your rig.

This pump-and-motor-based system increases response time compared with traditional actuators because the trailer brakes are triggered when you apply the brakes in the tow vehicle, as opposed to when the trailer pushes against the hitch ball. This not only gives you faster, more efficient braking, but it also eliminates the pushing sensation that occurs in setups that use standard surge brake actuators.

Hydrastar actuators are also beneficial because, unlike standard surge couplers, they allow you to activate your brakes when reversing down an incline, such as a boat ramp. Having the ability to brake in reverse gives you more control and prevents wear on your tow vehicle.

Hydrastar Installation

Hydrastar Installation Diagram

This Hydrastar electric-over-hydraulic brake actuator will give you years of trailer-stopping performance. The actuator mounts on your trailer's frame with the included stainless steel hardware. Then it splices into the trailer's wiring and connects to your hydraulic brake lines from the 3/16" female port. Lines and fittings are sold separately.

Durable, Marine-Grade Construction

The Hydrastar Marine actuator is ideal for use on boat trailers. Just like other Hydrastar electric-over-hydraulic actuator models, this system is built of extruded anodized aluminum for superior corrosion resistance. The weathertight seals protect internal components from the elements. The Hydrastar Marine actuator also features marine-grade gaskets and stainless steel hardware that won't rust. These extra features make it perfect for marine applications.

This actuator also has a vented end plate that releases pressure, moisture, and heat to help prevent any internal damage. Unlike models that are unable to release heat and pressure, this vented actuator can be safely mounted inside of a compartment on your trailer. As a result, this actuator is great for gooseneck and fifth-wheel trailers where finding space on the tongue can be nearly impossible.

Brake Controller Compatibility

Not all electric trailer brake controllers will work with this electric-over-hydraulic brake actuator. See the following table to determine compatibility with common models of brake controllers. For best performance, it is recommended that you use an aftermarket electric brake controller rather than an OEM factory-installed controller.

ManufacturerVehicle Years/Controller ModelsCompatibleCompatible if Used with HBA-CAM
Brake ControllersDraw-TiteActivator (5100)Yes
Activator II (5500 or 5510)Yes
Activator III (5520)Yes
Activator IV (5504)Yes
HayesEnergize III (81741B)Yes
Energize III+ (HA81742B)Yes
Energize XPC (HA81745)Yes
Engage (HA81760)Yes
G2 Brake Boss (81792BB)Yes
Syncronizer (HA81725)Yes
Endeavor (81770)Yes
Genesis (HA81790)Yes
Blackbird (HA81726)Yes
HopkinsImpulse Digital (47325)Yes
Insight (HM47297)Yes
Brake Force (47225)No
Reliance (47284)No
Agility (47294 or 47295)No
MaxbrakeBrake ControllerYes
RedlineRedline TA900Yes
TekonshaProdigy (90185)Yes
Prodigy P2 (90885)Yes
Prodigy P3 (90195)Yes
Primus IQ (TK90160)No
PowerTrac (39523)Yes
Voyager (39510 or 9030)Yes
ValleyVA32812 BlackbirdYes
VA32811 PhantomYes

381-8066 Cargo Towing Solutions (formerly Carlisle) Hydra Star Marine Grade Electric-Hydraulic (EOH) Actuator - 1200 psi - Model MHBA-12

Customer Satisfaction Score:

Customer Reviews

Hydrastar Vented Marine Electric Over Hydraulic Actuator for Drum Brakes - 1,200 psi - HS381-8066

Average Customer Rating:  5.0 out of 5 stars   (11 Customer Reviews)

Anodized aluminum electric-hydraulic actuator lets you use your brake controller (sold separately) to activate your trailer's hydraulic brakes. Includes rust-resistant marine-grade gasket and stainless steel hardware. Vented plate releases heat.


Had a problem with first shipment , was resolved promptly


I ordered the brake controller yesterday I already have it today so it was here in one day quick service I don’t have time to put it on right now but when I do I hope to let you know how it works thank you . I Purchased a titan brake controller probably five years ago and it on a cattle trailer so I didn’t use it a whole lot and the motor went out on it very quick so I was disappointed in that brand and I thought I’d try this hydrastar system hope I have better luck with it . Thanks


I installed it in just a few hours, and set it to the most aggressive setting. My wife and I have wanted one for a few years after a few close calls pulling our boat. Well, weirdly enough, this product paid for itself in the first week. A car pulled out right in front of us on a highway. I was able to avoid the crash, that if this product was not on, we would have hit. Pulling a 10 thousand lb boat, one just cannot stop on a dime doing 60 mph. The next week on the way home from the lake, a moose stepped out onto the highway, once again, was able to stop! My wife is happy as we had a few close calls and she was very happy and it was money well spent. Wished we had bought it sooner.


etrailer as always has what I need, ships fast, and product is "as advertised"!
A pleasure to talk to the tech's when I have questions and even go as far as calling manufacturer to verify equipment selections.
Keep up the GREAT work.


Great reliable product. It handles my 12,000 lb. boat and trailer on wet or dry roads.


Unit work’s very well and was easy to install .I am looking forward to a wonderful safe trip pulling my 12,000 lb boat 600 miles north to San Juan Islands and British Columbia.








See what our Experts say about this Hydrastar Brake Actuator

  • Hydraulic Trailer Brakes are Slow to Release
    For hydraulic brakes that are dragging or slow to release it could be a number of issues. If you have used the wrong type of fluid required by your brake set up, that could cause the problem. There may also be a foreign object in the master cylinder blocking the correct flow of fluid. For either of these you will need to drain the system, check for foreign objects and remove them, flush the system and refill/bleed the system using the correct brake fluid. If your system has a parking brake...
    view full answer...
  • Is HydraStar Electric Over Hydraulic Compatible Integrated Brake Controller of 2015 Chevy Silverado
    Your 2015 Chevy Silverado integrated brake controller would work fine with this actuator # HS381-8066 as in 2015 Chevy started installing brake controllers in their trucks that are compatible with electric over hydraulic actuators. Without knowing how your trailer is setup already it's hard to say exactly what you would need, but if you check out the help article I attached you will see a guide that will walk you through the whole process of adding EOH brakes to a trailer.
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  • Trailer Brakes Lock Up After Using an Electric Over Hydraulic Actuator and 2012 Dodge Ram 3500
    The first thing I recommend checking is the output setting on the brake controller. If adjusting the power level does nothing to solve the problem, then we can work out way back. Check the vehicle and trailer side connectors for any dirt or corrosion because this can cause a short. Next move on to the trailer and check the wiring for the actuator. The unit must be wired like in the diagram I have included. If there is a short in the breakaway wiring, the pin is pulled out from the switch,...
    view full answer...
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  • Electric Over Hydraulic Actuator Recommendation for Converting Electric Trailer Brakes
    To convert your trailer's electric brakes to electric over hydraulic, you will need a couple of things along with the Redline Hayes Hydraulic Drum Brake Assembly you referenced in your question. For an electric over hydraulic actuator, I recommend the HydraStar Vented Marine, part # HS381-8066. This system has a rust-resistant marine-grade gasket and stainless steel hardware. The design also includes a vented plate which prevents the system from getting too hot. I have included a video...
    view full answer...
  • Hydrastar Actuator for Drum Brakes Work With Ford F600 Converted Into Trailer
    I'm assuming you're using the F600 axles and brakes as part of that trailer. If that is the case, we do not have anything that is designed for vehicle brakes or any information on the output pressure required for your F600 brakes. I suppose if you knew 1,200 psi was correct then the # HS381-8066 would work, but this is not something that has been tested. If your trailer conversion replaced the axles and drum brakes with trailer axles/brakes then you would be able to use the Hydrastar without...
    view full answer...
  • Compatibility and Opinion on Electric Brakes On a Boat Trailer
    Surge braking systems are a good system, but they don't let you control your braking in the same way as an electric braking system. I personally do recommend switching to electric because of the ease of use and cost savings. The only draw back to consider is that you need to unplug your trailer prior to backing into the loading ramp to launch or load your boat. Obviously electricity and water don't mix well and people have avoided electric brakes on boat trailers due to this in the past,...
    view full answer...
  • Compatibility of Prodigy P2 Brake Controller with Hydrastar EOH Actuator for Drum Brakes
    Your Prodigy P2 # 90885 is compatible with the Hydrastar electric over hydraulic actuators like # HS381-8066. You will not need the adapter like you would for a factory brake controller. It is directly compatible with that brake controller. If you scroll down the product page on the actuator you will see the compatibility chart that confirms this.
    view full answer...
  • Recommended Electric Over Hydraulic Actuator For Triple Axle Boat Trailer
    For your triple axle boat trailer, I recommend the HydraStar Vented Marine Electric Over Hydraulic Actuator for Drum Brakes - 1,200 psi # HS381-8066. If you want a complete kit, I recommend the HydraStar Marine Electric Over Hydraulic Actuator w/ Breakaway and 7-Way RV Harness - 1,200 psi # HS381-9066. Electric over hydraulic actuators are not compatible with every brake controller, so you will want to see the compatibility listed on the product page. I recommend the Tekonsha Prodigy...
    view full answer...
  • Electric-Over-Hydraulic Actuator and Breakaway Battery Kit Recommendations for 3,500 lb Trailer
    Happy 4th to you as well, Jerry! Since you already have your 2017 Toyota Tundra set up for electric brakes you just need to add an electric-over-hydraulic (EOH) actuator and the breakaway battery kit. Here is what I recommend for your application: - Actuator for Drum Brakes # HS381-8066 - Actuator for Disc Brakes # HS381-8067 - Breakaway Battery Kit # 20400 Attached are some review and installation videos for you to check out!
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  • Recommended Actuator and Wiring for Boat Trailer Upgrade From Surge Brakes
    To add EOH to a surge brake trailer, you will need to add the electric components to make the actuator function. You can get the etrailer 7-Way Molded Trailer Plug with Junction Box # E99011 and then wire your actuator into that junction box. You will be able to simply connect to your current hydraulic brake lines. For your actuator, I recommend the HydraStar Vented Marine Electric Over Hydraulic Actuator for Disc Brakes - 1,600 psi # HS381-8067 or the HydraStar Vented Marine Electric...
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  • Best Disc Brake Actuator for Triple Axle Drum Brakes
    For just the actuator by itself the correct Hydrastar is the part # HS381-8066 that you referenced as it's pressure rating is correct for drum brakes and is rated for up to three brake axles. For a kit that includes the needed junction box, 7-way connector, a junction box for easy wiring and other various terminals for an easy install you'd instead want the part # HS381-9066 as all of that is included with this kit. Then for a triple axle brake line kit we have the Hydrastar kit part...
    view full answer...
  • Is Adapter HBA-CAM Needed For 2019 GMC Sierra Factory Brake Controller & HydraStar Actuator
    For your 2019 GMC Sierra 2500 with the factory brake controller, you will not need to use the HydraStar Electric Over Hydraulic Actuator Adapter Module # HBA-CAM along with the HydraStar Vented Marine Electric Over Hydraulic Actuator - 1,200 psi # HS381-8066. HydraStar has confirmed for us that the factory controllers on 2018 and up GMC/Chevy trucks are compatible with these actuators.
    view full answer...
  • Recommended Hydraulic Actuator For Disc Brakes On Tandem Trailer
    I recommend the HydraStar Electric Over Hydraulic Actuator for Disc Brakes, part # HBA16. This has a maximum output pressure of 1,600 psi and will work with your tandem trailer. The HydraStar Vented Marine Electric Over Hydraulic Actuator for Drum Brakes, part # HS381-8066 you mentioned is designed to work with drum brakes, so it is not a fit for your 10-inch disc brakes.
    view full answer...
  • What is Difference Between HydraStar Actuators # HBA-12 and HS381-8066
    The big difference is that the # HS381-8066 is for marine applications so that means it has stainless steel hardware and a marine grade gasket which allows it to stand up a lot better to corrosion than the # HBA-12.
    view full answer...
  • Recommended Electric Over Hydraulic System for Kaufman 6 Max Car Carrier
    For your Kaufman 6 Max Car Carrier Trailer, I recommend the HydraStar Marine Electric Over Hydraulic Actuator w/ Breakaway and 7-Way RV Harness - 1,600 psi # HS381-9067 if your trailer has disc brakes. If your trailer has drum brakes then I recommend the HydraStar Marine Electric Over Hydraulic Actuator w/ Breakaway and 7-Way RV Harness - 1,200 psi # HS381-9066. If you just need the actuator itself, then you will use # HS381-8067 for disc or # HS381-8066 for drum.
    view full answer...
  • Brake Controller for Electric Over Hydraulic Brakes
    I do have a great option for you, however your Tekonsha Prodigy RF Wireless Brake Controller 90250 is not compatible with electric-over-hydraulic brakes. Unfortunately you will not be able to use the controller with your trailer after converting the braking system. For an excellent brake controller that is compatible with EOH brakes I recommend taking a look at the Tekonsha Prodigy P2 # 90885. This is a wired proportional controller that will activate the trailer brakes at the same time...
    view full answer...
    Image 1 for
  • Troubleshooting OEM Brake Controller Installation in 2012 Ram 1500
    The OEM-supplied trailer brake controller for the 2012 Ram 1500 is designed to work only with electric drum brakes. It will not work with electric-over-hydraulic actuators such as HydraStar drum brake model # HS381-8066 or the disc brake model # HS381-8067. If you have an EOH setup on the trailer you will need an aftermarket controller that is compatible with it, such as the Prodigy P2 # 90885 or the P3 # 90195, as well as a wiring adapter # 3021-P if the truck came with a factory 7-way. You...
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  • Can Electric Over Hydraulic Brake Actuator Be Fully Submerged
    I spoke with my contact at Titan about the BrakeRite II # T4813102. He confirmed that they do not recommend completely submerging the BrakeRite. I also spoke with Dexter Axle to see if their Electric Over Hydraulic Brake Actuators, # K71-651, can be submerged. They confirmed that their actuators are not designed to be fully submerged. Though also not recommended to be submerged, the most likely contender to hold up to being fully submerged is the Hydrastar Marine Grade Electric Over...
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  • Adding Electric Over Hydraulic Drum Brakes to a Trailer
    With 6,000 pound axles they must take 12 x 2 inch assemblies. For a left and right side pair of assemblies you can use # AKFBBRK-7. We do not have an option for self-adjusting brakes in this size with a single-servo design. For an actuator I recommend the Hydrastar # HS381-9066. This unit is rated to 1,200 psi so it provides a little extra kick above the 1,000 psi units. Since you have a couple of 6,000 pound axles you're going to want the best to slow the loaded trailer down. It also...
    view full answer...
  • Troubleshooting EOH Brakes Not Activating
    The first thing I would do is check for power. Using a circuit tester like # PTW2993 check to see if 12V power is running to the # HS381-8066 when you use your manual override on the brake controller. If you have power here and no brakes it is likely the actuator. Go ahead and call Hydrastar directly to see about warranty work since it is under a 2-year warranty. If you do not have power here then it is a problem with the trailer connector or on the vehicle side. Go ahead and check both...
    view full answer...
  • Can Motor Be Replaced for Hydrastar Electric Over Hydraulic Actuator
    If the motor on your Hydrastar Electric Over Hydraulic Actuator went out then you'll need to replace the entire actuator as the motor is not a replaceable part according to my contact at Hydrastar. You'll just want to choose the actuator with matching specs to what you currently have: Standard: 1,000 psi - # HBA-10 1,200 psi - # HBA-12 1,600 psi - # HBA16 Vented: 1,000 psi - # HS381-8065 1,200 psi - # HS381-8066 1,600 psi - # HS381-8067 Attached are a few review videos for you to check out.
    view full answer...
  • Air Line Connection for Hayes Air Actuated Trailer Brake Controller HA100400C
    The Hayes Air Actuated Trailer Brake Controller # HA100400C will connect to your RV's air brakes by installing 3/16 or 1/4-inch diameter S.A.E. approved tubing like # RM450700 between the brake controller and the vehicle service line. For brake systems with primary and secondary service lines you'll connect to the existing two-way check valve between the two service lines and install the tubing from the output side of the check valve to the brake controller. The two-way check valve should...
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    Image 1 for
  • Comparing the HydraStar Hydraulic Actuator and the Titan BrakeRite Hydraulic Actuator
    It looks like you have certainly done your research in regards to the HydraStar Electric Over Hydraulic Actuator and the Titan BrakeRite EHB Electric-Hydraulic Actuator. In regards to repose time, this goes to the Titan BrakeRite EHB with a response time of .3 seconds whereas the HydraStar Electric Over Hydraulic Actuator has a response time of .8 seconds. This is due to the five vs three piston pumps that each respective units use. In regards to the Titan BrakeRite EHB Electric-Hydraulic...
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  • Recommended Trailer Braking for Air Brake System On Motorhome to Tow Vehicle
    We do not have any hoses compatible with your Glad Hands connectors nor have an adapter. The closest thing we have is the Replacement Air Jumper for SMI Air Force One Supplemental Braking System # SM99666. We do not have any parts for air brakes on trailers but we do have some other options that wouldn't utilize the Glad Hand connections, but also won't harm them for that connection to still function. All we can offer is a brake controller like the Hayes Air Actuated Trailer Brake Controller...
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Info for this part was:

Employee Jeff D
Installed by:
Jeff D
Employee Jameson C
Expert Research:
Jameson C
Employee Leah S
Edited by:
Leah S
Employee Amanda M
Written by:
Amanda M
Employee Manda E
Updated by:
Manda E

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