Patent ID: 8349278

Claim:
Apparatus for withdrawing liquid samples from respective ones of a plurality of containers or for discharging liquid samples into respective ones of a plurality of containers, the apparatus comprising: a rack for holding the containers, a device for withdrawing a liquid sample from a selected one of the containers or for discharging a liquid sample into a selected one of the containers, the device being mounted on the apparatus above the rack, and being moveable relative to the rack for selective alignment with a selected one of the containers, the device comprising: a cannula adapted for extending into the selected container and to withdraw or discharge the liquid sample from or to the selected container, an abutment means adapted to engage one of the selected container and a closure element thereof, a drive shaft, a first drive transmission element mounted on the drive shaft for receiving drive therefrom for urging the cannula into the selected container, a second drive transmission element for urging the abutment means into engagement with one of the selected container and the closure element thereof, and a clutch means coupling the second drive transmission element to the first drive transmission element for transmitting drive from the drive shaft to the abutment means through the first and second drive transmission element to simultaneously urge the cannula and the abutment means towards the selected container, the clutch means being responsive to the abutment means engaging one of the selected container and the closure element thereof for decoupling the second drive transmission element from the first drive transmission element, so that the cannula is urgeable relative to the abutment means by the first drive means into the selected container, wherein the clutch means is formed by the first and second drive transmission elements and comprises an engagement means extending from one of the first and second drive transmission elements for releasably engaging a corresponding receiving means on the other one of the first and second drive transmission elements for selectively transmitting drive from the first drive transmission element to the second drive transmission element.