Level means

Claim 2

A platen raising, lowering, and leveling system comprising a platen, ram means for positioning said platen at a preselected position, said ram means including master ram means and slave ram means, valve means associated with each ram means to admit and exhaust fluid pressure to and from each ram means, control means for each valve means, means to generate one of a multiplicity of command signals to the control means associated with he valve means controlling said master ram means, said control means, in response to a command signal, operating said master ram valve means until said master ram means attains a desired position corresponding to the value of said command signal, position sensing means associated with said platen to determine the actual position of said platen, means responsive to said positionsensing means to generate an error-correcting signal to the control means associated with the valve means controlling said master rams means said associated control means operating its valve to correct any error in the position of the master ram signal-generating means responsive to the pressure in said master ram and adapted to transmit a signal to each other control means as a function of the fluid pressure in the master ram means, each of said other control means operating its valve means in response to said signal so that each slave ram means attains a pressure corresponding to the pressure of said master ram means, means to compare any difference in the actual extended level of at least one slave ram on the one hand with the actual extended level of at least one other slave ram on the other hand, means for generating an error-correcting signal as a function of any level differences between said slave rams, and means for feeding the error-correcting signal to said other control means to modulate and correct the signal transmitted to said other control means from the pressure-responsive signal-generating means.

Claim 3

A platen raising, lowering, and leveling system comprising an assembly platen and a support platen, said platens being hinged together along one edge, ram means for each platen having Piston rods pivoted adjacent the opposite edge of each platen and adapted to pivot each platen between substantially horizontal and substantially vertical positions, said ram means including master ram means and slave ram means, valve means associated with each ram means to admit and exhaust fluid pressure to and from each ram means, control means for each valve means, means to generate one of a multiplicity of command signals to the control means associated with the valve controlling said master ram means, said control means in response to a command signal operating said master ram valve means until said master ram means attains a desired position corresponding to the value of said command signal, position-sensing means associated with each of said platens to determine the actual positions of said platens, means responsive to said position-sensing means to generate an error-correcting signal to the control means associated with the valve controlling said master ram means, said associated control means operating its valve to correct any error in the position of the master ram means, signal-generating means responsive to the pressures in said master ram means and adapted to transmit a signal to each other control means as a function of the fluid pressure in the master ram means, each of said other control means operating its valve means in response to said signal so that each slave ram means attains a pressure corresponding to the pressure of said master ram means, means to compare any differences in the actual extended level of at least one slave ram on the one hand with the actual extended level of at least one other slave ram on the other hand, means for generating an error-correcting signal as a function of any level differences between said slave ram means, and means for feeding the error-correcting signal to said other control means to modulate and correct the signal transmitted to said other control means from the pressure-responsive signal-generating means.

Claim 4

A platen raising, lowering, and leveling system comprising an assembly platen and a support platen, said platens being hinged together along one edge, ram means for each platen having Piston rods pivoted adjacent the opposite edge of each platen and adapted to pivot each platen between substantially horizontal and substantially vertical positions, said ram means including master ram means and slave ram means, valve means associated with each ram means to admit and exhaust fluid pressure to and from each ram means, control means for each valve means, means to generate one of a multiplicity of command signals to the control means associated with the valve controlling said master ram means, said control means in response to a command signal operating said master ram valve means until said master ram means attains a desired position corresponding to the value of said command signal, position-sensing means associated with each of said platens to determine the actual positions of said platens, means responsive to said position-sensing means to generate an error-correcting signal to the control means associated with the valve controlling said master ram means, said associated control means operating its valve to correct any error in the position of the master ram means, signal-generating means responsive to the pressures in said master ram means and adapted to transmit a signal to each other control means as a function of the fluid pressure in the master ram means, each of said other control means operating its valve means in response to said signal so that each slave ram means attains a pressure corresponding to the pressure of said master ram means, means to compare any differences in the actual extended level of at least one slave ram on the one hand with the actual extended level of at least one other slave ram on the other hand, means for generating an error-correcting signal as a function of any level differences between said slave ram means, and means for feeding the error-correcting signal to said other control means to modulate and correct the signal transmitted to said other control means from the pressure-responsive signal-generating means.

Claim 5

A platen raising, lowering, and leveling system according to claim 1, wherein said means to compare any differences in the actual extended level of at least one slave ram on the one hand with the actual extended level of at least one other slave ram on the other hand comprises a plurality of reservoir means connected together by fluid conduit means, each of said reservoir means having float means contained therein, each of said fluid reservoir means being pivotally connected to the platen adjacent one of the slave ram means, and wherein said means for generating an error-correcting signal as a function of any level differences between said slave ram means comprises rod means connected to each of said float means, coil means surrounding each rod means to generate said error-correcting signal as a function of any differences in level of said float means.

Claim 6

A platen raising, lowering, and leveling system according to claim 1, wherein said position-sensing means associated with said platen to determine the actual position of said platen comprises a gear segment fixed to said platen, spur gear means meshing with said segment gear, and wherein said means responsive to said position-sensing means includes an angular motion potentiometer driven by said spur gear which generates said error-correcting signal to the control means associated with the valve controlling said master ram means.

Claim 7

A platen raising, lowering, and leveling system comprising a platen, ram means for positioning said platen at a preselected position, said ram means including master ram means and slave ram means, means to admit and exhaust fluid pressure to and from each ram means, means to sense the fluid pressure in said master ram means and to provide that pressure in each of said slave ram means, means to compare any differences in the actual extended level of at least one slave ram on the one hand with the actual extended level of at least one other slave ram on the other hand, and means to correct any level differences between said sLave rams.

Claim 8

A platen raising, lowering, and leveling system comprising a platen, ram means for positioning said platen at a preselected position, said ram means including master ram means and slave ram means, means to admit and exhaust fluid pressure to and from each ram means, means to sense the fluid pressure in said master ram means and to provide that pressure in each of said slave ram means, means to compare any differences in the actual extended level of at least one slave ram on the one hand with the actual extended level of at least one other slave ram on the other hand, and means to correct any level differences between said sLave rams.