Abstract: A trolley assembly includes a first trolley. The first trolley includes a first assembly including a first positioning system. The first positioning system includes a first housing and a first rotatable element. The first trolley also includes a second assembly separate from the first assembly and removably coupled with the first assembly via a drilling mast. The second assembly includes a second positioning system. The second positioning system includes a second housing and a second rotatable element. The first trolley further includes an actuation device disposed in at least one of the first positioning system and the second positioning system. Upon operation of the actuation device, the actuation device rotates the drilling mast relative to each of the first housing of the first positioning system and the second housing of the second positioning system to dispose the drilling mast at a plurality of work positions.

Abstract: A check valve includes a valve body, a pair of stoppers, a hinge pin, and one or more flappers. The valve body includes an inlet end, an outlet end, and an inner surface that defines a flow passage between the inlet end and the outlet end. The inner surface further defines a valve seat adjacent the inlet end. The stoppers are integrally formed on the valve body inner surface, and each has a first end and a second end. The hinge pin is disposed within each hinge pin opening and extends across the flow passage. The flappers are disposed within the flow passage and are rotationally mounted on the hinge pin. Each of the one or more flappers is rotatable between a closed position, in which the flapper engages the valve seat, and a full-open position, in which the flapper engages the pair of stoppers.

Abstract: A check valve includes a valve body, a pair of stoppers, a hinge pin, and one or more flappers. The valve body includes an inlet end, an outlet end, and an inner surface that defines a flow passage between the inlet end and the outlet end. The inner surface further defines a valve seat adjacent the inlet end. The stoppers are integrally formed on the valve body inner surface, and each has a first end and a second end. The hinge pin is disposed within each hinge pin opening and extends across the flow passage. The flappers are disposed within the flow passage and are rotationally mounted on the hinge pin. Each of the one or more flappers is rotatable between a closed position, in which the flapper engages the valve seat, and a full-open position, in which the flapper engages the pair of stoppers.