Hydraulic Trailer Master Cylinder


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Hydraulic Trailer Master Cylinder, Override, Single, Tandem

Hydraulic trailer master cylinder, 3/4 inch and 7/8 inch to suit 2,000kg override couplings. Best suited to 14-inch, 15-inch and 16-inch wheels.

The trick to an efficient hydraulic braking system is to bleed and adjust brakes correctly. Once the brakes bleed, tighten the nut on the back of the brake lever.

Two types of hydraulic trailer brake master cylinders are now available for purchase.

  1. 3/4 inch – Hydraulic Single Brake Trailers.
  2. 7/8 inch – Hydraulic Tandem Trailers.

A zinc bracket is required brake for hydraulic braking systems.

  1. Fit the master cylinder bracket on the rear bolt mounts
  2. Bolt hole mounts are 54mm between centres
  3. Select 1/2-inch bolts that bolt right through your bracket, coupling and drawbar
  4. Disconnect the parking brake
  5. Adjust the lower nut 2mm from the back of the override, then lock it off.

Precise instructions can be found from Al-ko here

Further, we have more information from our engineer

  • you must have at least 2mm free play, between 2mm and 5mm, when the hydraulic brake pads start to wear
  • if there is no free play, as soon as the brakes start to work and get a little warm, you will start to get brake build-up, increasing heat and burning out your brakes or even popping the seals in the master cylinder

3/4 inch Master Cylinder

The 3/4 inch master cylinder is the crucial braking component used on single-axle braked trailers. These trailers have two-wheel cylinders.

3/4 inch refers to the piston bore size.

Further, you’ll also buy a wide range of braking system components like 9-inch hydraulic brake shoes, hydraulic drum brakes, and even electric brake parts.

7/8 inch Master Cylinder

The 7/8-inch master cylinder is the crucial braking component used on tandem trailers with four hydraulic cylinders.

The plastic bowl version requires regular replacement as is susceptible to UV degradation.

What type of brake fluid should I use?

DOT 3 or DOT 4 is what should be used in your boat trailer. This type of hydraulic oil does not absorb water, and the silicone in the DOT 5 makes the seals swell and can bind up caliper pistons.

Purchase spare parts and other trailer parts here

Additional information

Master Cylinder



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