Drive mechanism of a pair of forging or stretching rollers

Claim 1

In a drive mechanism for a pair of rollers comprising a pair of rollers operatively connected with each other; a main drive shaft upon which is mounted one of said rollers; a hydraulic motor engaging said shaft; a flowrate-adjustable axial piston hydraulic pump adjusted by tilting; means for adjusting the flowrate of said pump; pressure fluid; a first connecting means for connecting said hydraulic pump with said hydraulic motor; a fluid reservoir; a second connecting means for connecting said hydraulic motor with said fluid reservoir; a third connecting means for connecting said fluid reservoir with said hydraulic pump; a first switching means interposed in said first and second connecting means for controlling said hydraulic motor; and a main motor operatively connected to and driving said hydraulic pump; the improvement comprising: said means for adjusting the flowrate of said pump comprises a first hydraulic cylinder; hydraulic means for actuating said first switching means; a fourth connecting means connecting said first connecting means between said first switching means and said hydraulic motor with said fluid reservoir; a check valve in said fourth connecting means; a second switching means operated by means of contacts for simultaneously operating said first hydraulic cylinder and said hydraulic means, said second switching means being interposed in said fourth connecting means between said check valve and said fluid reservoir; a hydraulic accumulator in said fourth connecting means between said check valve and said second switching means; and said first switching means being arranged so that when said motor is operating, said pressure fluid flows from said pump through said first connecting means to said motor and from said motor back to said fluid reservoir, and when said motor is stopped said pressure fluid only flows from said pump directly to said fluid reservior, said first and second connecting means being positively isolated from the fluid flow and from each other.