not being shown in detail in fig3 however as shown in fig4 this actuating mechanism is located above the maximum height of the cows between the top end of gate 22 and a circularly disposed upper carrier member 21 associated with the rear barrier or milking stall delimiting means 20 fig4 whereby this actuating mechanism does not occupy additional space outside the milking platform or any room within the cows 39 range of movement in milking position 32 activation of the double acting fluid cylinder e g by way of air or hydraulic oil in the appropriate timed sequence in dependence on the rotary position of the rotary milking platform is effected in a conventional manner by a cam controlled valve 42 fig3 via a suitably contoured camming surface 43 fig1 located on the milking platform 10 a discussion of the details of such camming surfaces will be unnecessary because they are well known to the person skilled in the art it is noted however that actuating member 30 biases the gate or headlock 22 in a direction towards a cow present in milking position 32 with a relatively low force so as to not place the cow under excessive constraint on the other hand at the end of the.