Brake system

Claim 1

A brake system comprising a master brake cylinder, a first brake line (I) and a second brake line (II) connected to said master brake cylinder which communicates with first and second wheel brake cylinders (5 and 6) for rear wheels and third and fourth wheel brake cylinders (11, 12) respectively for front wheels, a first control valve (8) in said first brake line upstream of a first shut-off valve (9), said first control valve and said first shut-off valve being in an open position for normal braking, a first check valve (20) in a first by-pass line from said first and second wheel brake cylinders which by-passes said first control valve (8) and said first shut-off valve (9), by which brake pressure in said first and second wheel cylinders (5 and 6) is reduced, said second brake line (II) including a second shut-off valve (16) in a line (14) to said third wheel brake cylinder (11), a third shut-off valve (17) in a line to said fourth wheel brake cylinder (12), a second control valve (13) is provided in a line (10) of said second brake line (II) upstream of said second and third shut-off valves (16 and 17), second and third check valves (21) and (22) in a second by-pass line between said third and fourth wheel brake cylinders which by-passes said second and third shut-off valves (16 and 17) and said second control valve (13) by which brake pressure in said third and fourth wheel brake cylinders (11 and 12) passes for a pressure reduction and pressure buildup, said first shut-off valve (9) is connected to a first branch line which is connected to said first brake line (I), said first branch line extends from said first brake line via a first pressure reduction valve (32) to a first reservoir (33), said first reservoir connects with a first return pump (35) via a first pressure build-up valve (34), said first return pump (35) has a first output line which connects with said first brake line (I) downstream of said first control valve (8); for pressure buildup and reduction in said second brake line (II), a second branch line (24) branches off from said second brake line (II) upstream of said second and third shut-off valves (16 and 17), said second branch line extends to a second reservoir (26) via a second pressure reduction valve (25), said second reservoir connects with a second return pump (28) via a second pressure build-up valve (29), said second return pump has a second output line which connects with said second brake line (II) between said second and third shut-off valves (16 and 17) and said second control valve (13), each of said first and second pressure reduction valves (32 and 25) and each of said first and second pressure build-up valves have an open position and a blocking position whereby brake pressure on the first and second brake lines (I) and (II) to the first, second, third and fourth wheel brake cylinders is controlled by the first and second pressure reduction valves (32 and 25) to prevent front and rear wheel slide and the pressure in the first and second brake lines (I) and (II) to the respective wheel brake cylinders is controlled by the first and second pressure buildup valves (34 and 29) to prevent the respective wheels from spinning.