All terrain vehicle with dual hydraulic brake system

An all terrain vehicle comprising:

• a chassis;
• a pair of front wheels mounted to the chassis;
• a pair of rear wheels mounted to the chassis;
• an engine carried by the chassis, the engine being connected to a drive train supplying motive power to at least some of the wheels;
• and
• a dual hydraulic brake system including:
• a first master cylinder, a pair of front hydraulic brake units, each front brake unit being associated with one of the front wheels, a rear brake unit associated with the rear wheels, a first hand-operable brake lever operatively connected to the first master cylinder, and a first set of hydraulic connections among the first master cylinder and the brake units so that when the first brake lever actuates the first master cylinder all three brake units are actuated to brake both the front wheels and the rear wheels;
• and
• a second master cylinder, a second brake lever operatively connected to the second master cylinder, and a second set of hydraulic connections between the second master cylinder and only the rear brake unit, the second set of hydraulic connections being separate from and sealed from the first set of hydraulic connections so that actuation of the second master cylinder by the second brake lever actuates only the rear brake unit to brake the rear wheels independently of the front wheels.

An all terrain vehicle comprising:

• a chassis carrying a straddle-type seat which is sufficiently narrow to be straddled by a rider;
• a pair of front wheels mounted to the chassis, and handlebars connected to the front wheels for steering the vehicle;
• a pair of rear wheels connected to a common rear drive axle mounted to the chassis;
• a laterally extending footrest on each side of the chassis;
• an engine carried by the chassis generally beneath the straddle-type seat and generally between the footrests, the engine being connected to a drive train supplying motive power to at least some of the wheels;
• and
• a dual hydraulic brake system including:
• a first master cylinder,
• a first hydraulic fluid reservoir associated with the first master cylinder,
• a hand-operable brake lever mounted to the handlebars and operatively connected to the first master cylinder,
• a second master cylinder,
• a second hydraulic fluid reservoir associated with the second master cylinder,
• a foot-operable brake lever carried by the chassis near one of the footrests and operatively connected to the second master cylinder,
• a pair of front hydraulic disc brake units, each front disc brake unit being associated with one of the front wheels and including a rotor carried by such wheel and a disc brake caliper positioned to selectively engage such rotor,
• a rear disc brake unit including a rear disc brake rotor carried by the rear drive axle and a rear disc brake caliper positioned to selectively engage the rear disc brake rotor, the rear disc brake caliper including a caliper body and a stepped piston disposed within a stepped bore formed in the caliper body, the stepped piston and the stepped bore together defining first and second hydraulic fluid chambers, the first and second chambers being sealed from each other,
• a first set of hydraulic connections among the first master cylinder, the front brake units and the first hydraulic fluid chamber of the rear brake unit so that when the hand-operable brake lever actuates the first master cylinder all three brake units are actuated to brake both the front wheels and the rear wheels;
• and
• a second set of hydraulic connections between the second master cylinder and the second hydraulic fluid chamber of the rear brake unit, the first set of hydraulic connections being separate from, and sealed from, the second set of hydraulic connections so that when the foot-operable brake lever actuates the second master cylinder the rear brake unit is actuated without actuating the front brake units, thereby braking the rear wheels independently of the front wheels.

An all terrain vehicle comprising:

• a chassis carrying a straddle-type seat which is sufficiently narrow to be straddled by a rider;
• a pair of front wheels mounted to the chassis, and handlebars connected to the front wheels for steering the vehicle;
• a pair of rear wheels connected to a common rear drive axle mounted to the chassis;
• a laterally extending footrest on each side of the chassis;
• an engine carried by the chassis generally beneath the straddle-type seat and generally between the footrests, the engine being connected to a drive train supplying motive power to at least some of the wheels;
• and
• a dual hydraulic brake system including:
• a first master cylinder,
• a first hydraulic fluid reservoir associated with the first master cylinder,
• a first hand-operable brake lever mounted to the handlebars and operatively connected to the first master cylinder,
• a second master cylinder,
• a second hydraulic fluid reservoir associated with the second master cylinder,
• a second hand-operable brake lever carried by the chassis near one of the footrests and operatively connected to the second master cylinder,
• a pair of front hydraulic disc brake units, each front disc brake unit being associated with one of the front wheels and including a rotor carried by such wheel and a disc brake caliper positioned to selectively engage such rotor,
• a rear disc brake unit including a rear disc brake rotor carried by the rear drive axle and a rear disc brake caliper positioned to selectively engage the rear disc brake rotor, the rear disc brake caliper including a caliper body and a stepped piston disposed within a stepped bore formed in the caliper body, the stepped piston and the stepped bore together defining first and second hydraulic fluid chambers, the first and second chambers being sealed from each other,
• a first set of hydraulic connections among the first master cylinder, the front brake units and the first hydraulic fluid chamber of the rear brake unit so that when the first brake lever actuates the first master cylinder all three brake units are actuated to brake both the front wheels and the rear wheels;
• and
• a second set of hydraulic connections between the second master cylinder and the second hydraulic fluid chamber of the rear brake unit, the first set of hydraulic connections being separate from, and sealed from, the second set of hydraulic connections so that when the second brake lever actuates the second master cylinder the rear brake unit is actuated without actuating the front brake units, thereby braking the rear wheels independently of the front wheels.