Method and apparatus for inhibiting vehicle wheel locking

A control system for automatic control of a vehicle braking system to inhibit wheel locking:

• said control system comprising means for generating a first fluid pressure in dependence upon the rotation of a vehicle wheel;
• first valve means with an input for receiving brake pressure and an output for application of said brake pressure to a brake chamber associated with said wheel, the first valve means being settable into a first state where communication between the input and output is established so that the brake pressure can be transferred through said valve means to said brake chamber or a second state where communication between the input and output is blocked and the passage for brake pressure interrupted;
• a multi-port fluid valve control device having two positions and having a first control input for receiving said first fluid pressure, and a second control input for receiving a second fluid pressure, said second fluid pressure being the brake pressure, and the control device having a plurality of inputs and outputs, one of said outputs being connected to said first valve means to cause the latter to change to the second state when pressure appears at said one output, said control device being movable between said two positions to establish selective communication between various groups of said inputs and outputs in dependence upon the pressure differential between said first and second control inputs;
• and said control device being in its second state when pressure appears at said one output, and being at its first state when pressure does not appear at said one outlet and said control device being movable from said first state to said second state when the pressure at said second control input is greater than the pressure at said first control input.