an annular chamber 21 formed between a shoulder of the body 10 and a shoulder of the slide valve 11 this annular chamber 21 being itself in permanent communication with the first chamber 15 through a channel 22 pierced axially in the slide valve the annular chamber 21 communicates except for the first position of the slide valve resulting from an actuation of the master cylinder with the inlet 2a of the pump 2 via an aperture 10b of the body 10 of the distributor a non return valve 23 connected to the aperture 10b and to the inlet 2a of the pump prevents the loss of pressure by an escape of fluid towards the buffer reserve 6 while allowing fluid to be taken from this reserve by the pump 2 the outlet 2b from the pump is connected on the one hand to the annular chamber 18 through an aperture 10c of the body of the distributor on the other hand to a chamber 24 at high pressure and lastly to the inlet 7a of the electrovalve 7 through a restrictor 25 and a calibrated non return valve 26 preventing the loss of pressure in the receiver 3 by an escape of liquid towards the groove 18 which would delay the return of the distributor to its neutral position at the end of a wheelspin phase an aperture 10d pierced in the body 10 of the distributor causes the first chamber 15 to communicate except for the second position of the slide valve 11 with the outlet of the valve 26 and the inlet 7a of the electrovalve 7 moreover the first chamber 15 communicates permanently with the outlet 1a of the master cylinder 1 through an.