In a high pressure liquid system such as those commonly used for cleaning and scaling, a feed pump is connected in series with a high pressure pump. The discharge from the high pressure pump is controlled by a fail-safe pressure responsive valve which is responsive to feed pump pressure.

A sewer cleaner having a water pump with a clutch-less connection to an engine draws water from a tank having a baffle with an orifice. A valve arrangement directs the output from the pump to either a hose on a reel or recirculates to the tank. The flow rate through the orifice is less than the operating output of the pump so that the recirculated water combines with that flowing through the orifice to permit operation of a hydraulic system to rotate the hose reel.

A sewer and catch basin cleaner includes a system for injecting water under pressure into a sewer for cleaning same and a vacuum loading system for removing water and debris from the sewer catch basin. The cleaner includes a water storage tank for providing the cleaning water and a body for receiving the material removed from the catch basin or manhole. A water reclamation system is provided for replenishing the water tank from the body to facilitate uninterrupted operation of the device. The cleaner further includes a system for directing water from the body to the catch basin when sufficient water is in the water tank and a sensing arrangement for automatically keeping the desired amount of water in the respective containers. The body of the sewer cleaner of the present invention also includes a tailgate and an ejector plate for pushing debris from the body when cleaning is completed or when the body is full of debris. The ejector plate and tailgate are interconnected so that the tailgate is automatically raised as the ejector plate moves from the front toward the rear of the body. The tailgate includes an air pressurized seal to insure proper sealing to the body.

A sewer cleaning unit is disclosed which comprises a single tank assembly mounted on a wheeled vehicle. The single tank assembly has a substantially horizontal fixed divider forming a first tank portion adapted to carry and discharge a supply of water, and a second tank portion adapted to receive and hold debris, thus obviating the disadvantages of tank designs of the prior art. The unit may also be provided with hand-operated control means near the intake end of the conduit connected to the second tank portion and a control means connected to the reel for the hose from which water is discharged from the first tank portion, the reel control means and the hand-operated control means capable of being operated simultaneously by a single operator.

A method and apparatus provide for selective generation of pulses at water jets of a jet nozzle terminating a high pressure cleaning hose of a sewer cleaning machine. A ball valve is connected as a pressure bleeder to the high pressure side of the sewer cleaning machine pump and hence, the cleaning hose, for relieving pressure from the hose when the valve is open. A motor is connected to operate a rotatable element of the ball valve to automatically cycle the valve and generate a series of high pressure pulses at the water jets to thereby generate a hammering action to assist in penetration of blockages in a sewer being cleaned. The amplitude of the pulses is controlled by a second valve connected to the ball valve and the pulses preferably are generated at a frequency of approximately 3 hertz. The motor may be activated and deactivated by a blockage sensor which detects engagements of the nozzle with blockages formed by concentrations of refuse and debris within a sewer being cleaned.