Thor Forums

[Beau388]

All F-53 chassis (and most diesel pushers) use a hydro-boost or hydro-max brake booster system. This system uses the power steering pump to boost the brake line pressure. A vacuum type booster (even an 11.5" dual diaphragm vacuum booster) cannot supply the pressure and volume of brake fluid required for the anti-lock disk brake system to operate properly. The hydro-boost system is used on the 16,000/18,000 lb chassis and uses an accumulator to supply the necessary boost pressure should the power steering pump fail. The hydro-max system is used on the 20,500 lb and heavier chassis. The Hydro-max system uses a small electric pump to supply the boost fluid should the power steering pump fail.