Atwood Mobile Products mpd 85233 Manuale Utente

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messages following these symbols.

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avoid possible 

avoid possible

injury or death

injury and/or property damage

Provide these instructions to the consumer.

Consumer: Keep documents for future reference.

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• 

This system requires the solenoid wire leads be connected 

ONLY

into the tow

vehicle back-up light circuit.

are equipped with a solenoid back-up valve.

1. Connect the solenoid valve wire leads to the tow vehicle back-up

light circuit.

2. Connect trailer brake line to actuator.
3. Bleed brake system.

are not equipped with a solenoid back-up

valve. Contact Atwood (815-877-5700) for a Solenoid Back-up Valve
Kit - MPD 80376.

To install Atwood solenoid back-up valve -
1. Remove the plug in return port of master cylinder (this is the

upper port in the master cylinder).

2. Install straight barbed fitting (torque to 16-20 in/lb).
3. Install assembly in supply port of master cylinder (this is the lower

port in the master cylinder).

4. Connect the solenoid wire leads only into the reverse back-up

light circuit.

5. Connect trailer brake line to actuator.
6. Bleed brake system.

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• 

DO NOT

use brake fluid drained from brake system in refilling master cylinder.

Brake fluid can be contaminated from the system.

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• If brass orifice fitting is not installed, trailer-braking action may cause

vehicle(s) to shake during brake applications.

The brass orifice fitting installed in the master cylinder of the brake actuator
assembly must remain in the hydraulic circuit to the brakes of the trailer.

If the brass orifice fitting must be moved to accommodate plumbing for
a back up solenoid valve, it must be replaced in the hydraulic circuit in
line to brakes.

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• Contaminated brake fluid in system could plug brass orifice fitting. This

could render brakes inoperative.

Be especially careful to clean all fittings, tubing and threads between
master cylinder and brass orifice fitting. A very small particle of dirt or
thread sealant can plug the hole in the orifice. 

• Do not use Teflon

™

tape on fittings.

• If a liquid or paste thread sealant is used, keep it back two threads from end

of male fitting.

• Do not apply sealant to female threads. Clean female threads thoroughly.

BLEED BRAKE SYSTEM
1. Remove master cylinder filler cap and fill reservoir with DOT type 3

or 4 automotive brake fluid.

2. Check all hydraulic line fittings & connections to make sure they are

leak free.

3. At brake assembly, connect a bleeder hose to bleeder fitting on wheel

cylinder and submerge free end in a container with brake fluid. 

DO NOT

reuse brake fluid.

NOTE

:  Use power bleeder or bar with 2˝ diameter hitch ball attached.

Do not use breakaway cable for purpose of bleeding brake system. If
a power bleeder is used air pressure 35 PSI is most effective.

NOTE

: On tandem axle trailers, bleed brakes on rear most axle furthest

from the actuator first.

4. Loosen bleeder fitting at top of brake assembly.
5. Apply actuator and tighten bleeder fitting. Return actuator to

forward position. Again, loosen bleeder valve and apply actuator.
Repeat this procedure until fluid expelled from bleeder hose is free
of air bubbles. It is helpful to lower the trailer tongue to promote air
bubble movement in the brake tubing. It is also helpful to tap gently
along the brake tubing during brake bleeding to keep air bubbles
from sticking to the inside of the brake tubing. During this
procedure, master cylinder reservoir fluid level must be maintained
at no less than 1/2 full and no more than 1/2˝ from top of reservoir.

6. When no air bubbles are visible, close bleeder valve securely and

remove bleeder hose.

7. Repeat 

STEP

1-6 for remaining brake, then brakes on forward axle.

8. If installation is tandem axle with brakes on both axle, repeat

bleeding procedure on rear axle brakes for second time to assure
positive purging of all air in system.

9. After bleeding has been completed, re-check fluid level in master

cylinder.

9

Effective 12/04/07