Patent ID: 6247307
Filing Date: 2001-06-19
Classification: B66F,F15B

Abstract:
A hydraulic raising apparatus with automatic regulated speeds comprising:a working hydraulic cylinder 1 that is provided therein with a piston rod 2 and of which the interior is divided into a rodless side chamber 11 and a piston rod side chamber 12; said rodless side chamber 11 being connected to said piston rod side chamber 12 via a hydraulic circuit 14 with a check valve 141 that restricts hydraulic liquid flow in a single direction from said piston rod side chamber 12 to said rodless side chamber 11; said piston rod side chamber 12 being connected to a reservoir 4 through another hydraulic circuit 15 and a relief valve 7; said piston rod side chamber 12 being provided with a supply circuit 16 and a check valve 161 through which the hydraulic liquid of said reservoir 4 can flow into the piston rod side chamber 12 for replenishment; said rodless side chamber 11 being connected to the reservoir 4 through a return circuit 17 and a return valve 5; anda hydraulic pump 3 that is provided therein a piston rod 30 and of which the interior is divided into a rodless side chamber 31 and a piston rod side chamber 32; two oil channels 33 and 34 connecting said piston rod side chamber 32 with said rodless side chamber 31 through an adjustable relief valve 331 and a check valve 341 respectively so that the hydraulic fluid flow from said rodless side chamber 31 to said piston rod side chamber 32 must pass through said adjustable relief valve 331 and said oil channel 33 and the hydraulic fluid flow from said piston rod side chamber 32 to said rodless side chamber 31 must pass through said oil channel 34 and said check valve 341 in a single direction; said hydraulic pump 3 being connected to said reservoir 4 through a hydraulic circuit 35 and a check valve 351 which restricts hydraulic fluid flow in a single direction from the reservoir 4 to the pump 3; said working hydraulic cylinder 1 being connected to said pump 3 via an inlet circuit 8 with a safety valve 6;and characterized in that said working hydraulic cylinder can alter its working modes in said hydraulic circuits from a piston type to a spool type and vice versa to automatically adjust its raising speeds for various load conditions through said hydraulic circuit 14 and said check valve 141 interposed between said said rodless side chamber 11 and said piston rod side chamber 12, and through the supply circuit 16, the check valve 161, the hydraulic circuit 15 and the relief valve 7 disposed between the piston rod side chamber 32 in conjunction with said two oil channels 33 and 34 implanted between said piston rod side chamber 32 of said pump 3 and said rodless side chamber 31.