The present invention discloses a hydraulically-driven double-acting mud pump, comprising power motors, pressure oil pumps, a three-position four-way hydraulically-actuated directional valve, a hydraulic power end and a mud pump head, the power motors being connected to the pressure oil pumps in a conventional way, the pressure oil pumps being communicated with a port P of the three-position four-way hydraulically-actuated directional valve via a pipeline, a port T of the three-position four-way hydraulically-actuated directional valve being communicated with an oil tank via a pipeline, a port A and a port B of the three-position four-way hydraulically-actuated directional valve being both connected to the hydraulic power end, the hydraulic power end being connected to the mud pump head in a conventional way, a lower end of the mud pump head being communicated with a low-pressure manifold and two sides of the mud pump head being communicated with a high-pressure manifold. The hydraulically-driven double-acting mud pump of the present invention allows for more stable instantaneous flow and pressure of the discharged liquid from the mud pump and reduced fluctuation.

The present invention includes: a cylinder; a piston that is inserted in the cylinder and partitions an interior of the cylinder into fluid chambers and; guides that support the piston and guide movement of the cylinder, the guides including a first internal flow passage and a second internal flow passage; and nozzles communicating with the fluid chambers, respectively, wherein a pipe to communicate with a fluid pressure source is configured to switch between the external pipes, a flow passage from the fluid pressure source to the nozzles includes a short-circuit flow passage that short-circuits a flow passage communicating with the fluid pressure source and a flow passage not communicating with the fluid pressure source, and this short-circuit flow passage is provided with a throttle unit that throttles a flow passage.

The present invention discloses a hydraulically-driven double-acting mud pump, comprising power motors, pressure oil pumps, a three-position four-way hydraulically-actuated directional valve, a hydraulic power end and a mud pump head, the power motors being connected to the pressure oil pumps in a conventional way, the pressure oil pumps being communicated with a port P of the three-position four-way hydraulically-actuated directional valve via a pipeline, a port T of the three-position four-way hydraulically-actuated directional valve being communicated with an oil tank via a pipeline, a port A and a port B of the three-position four-way hydraulically-actuated directional valve being both connected to the hydraulic power end, the hydraulic power end being connected to the mud pump head in a conventional way, a lower end of the mud pump head being communicated with a low-pressure manifold and two sides of the mud pump head being communicated with a high-pressure manifold. The hydraulically-driven double-acting mud pump of the present invention allows for more stable instantaneous flow and pressure of the discharged liquid from the mud pump and reduced fluctuation.