A device for immobilising the spout on the ends of the trunnions, in a charging installation for a shaft furnace comprising a pivoting material distribution spout (1), the spout being connected to the supporting trunnions (2) by lugs (11) which engage in receptacles (21) formed in the trunnions and which are immobilised therein by pins (3) comprising at their end an eccentric nipple (31) engaging with a lug of the spout to hold the lug immobilised at the bottom of its receptacle, and locking means (4) for rotationally locking the pin. Each pin comprises, at the outer, opposite end thereof from the nipple, means (32) for rotational adjustment and tightening, so as to be able to press the nipple onto the lug of the spout with sufficient force by rotation of the pin, and the locking means comprise an indexing plate (41) connected for rotation to the end of the pin (3), the plate (41) further comprising teeth (416) arranged to cooperate with the corresponding teeth (421) of a lock (42) secured to the trunnion, in such a way that said lock can rotationally immobilise the pin in a plurality of circumferential positions of said pin.