Yup, its definetly feasible; it does mean that the horizontal and vertical crushers would both close at once, but as long as thats ok with you....

Forum user Tony Fowler has recently built a combined crusher called Kanzor, which, judging by pictures, uses a single windscreen wiper motor with a threaded rod attached to operate both sets of claws:

http://s31.photobucket.com/albums/c367/ayrshirerobotics/?action=view&current=kanzor.jpghttp://s31.photobucket.com/albums/c3...ew&current=kan zor.jpg

As long as you have three pivot mounting points on the actuator tip (two on one axis and one on another) it can be done

(Just to avoid any confusion, that picture linked above is not mine, it was on Tonys profile before he updated it and I saved it to my computer. Ill be taking it down soon since its not technically mine to distribute but it at least shows how it can be done)