Sewer Jetting Truck

Overview

A sewer jetting truck, often called a combination unit, clears blocked and silted sewers and storm drains using two tools at once. A high-pressure water jet scours the pipe and breaks up the blockage, and a powerful vacuum lifts the loosened sludge and water out of the line into an onboard tank. Carrying both functions on one chassis lets a crew flush a pipe and immediately recover the debris, rather than washing it downstream. The truck carries a clean water supply for jetting and a debris tank for the recovered material.

The vehicle joins the Cab and Chassis, a heavy tandem-axle cab and frame, with the Chassis Powertrain, whose diesel engine both drives the truck and powers the work equipment through a split-shaft PTO. The Clean Water Tank holds clean water, the Jetting System pressurizes it, the Vacuum System recovers the spoil into the Debris Tank, and the Vacuum Boom and Reels positions the vacuum over the access point. The crew runs the work from the Control System.

Chassis and powertrain

The Main Frame is a heavy box-section steel frame rated for the combined weight of the water and debris tanks, which together can exceed 30,000 lb when full. A conventional Cab seats the crew ahead of the equipment body. The Chassis Engine is an 11 L inline-six diesel producing 450 hp from a cast iron Engine Block with wet liners, sized for sustained high-power pump duty rather than peak road performance. The Automatic Transmission drives the wheels in transit, and the Cooling System system is oversized because the engine runs at high load while standing still during jetting.

The defining drivetrain feature is the Split-Shaft PTO, a split-shaft power take-off in the driveline. Its air-engaged PTO Clutch diverts engine power from the wheels to the PTO Shaft, which drives both the high-pressure water pump and the vacuum blower when the truck is parked at a work site.

Clean water supply

The Clean Water Tank is a Water Tank Shell of about 1,500-gallon capacity holding the clean water for jetting. Internal Water Baffle panels limit surge so the loaded truck stays stable, a Fill Connection connection with a backflow preventer allows hydrant refilling, and a Outlet Strainer keeps grit out of the pump. The water volume sets how long the crew can jet before refilling, since the jet consumes water continuously.

Jetting system

The Jetting System centers on a Triplex Plunger Pump, a three-plunger positive-displacement pump. Three ceramic Ceramic Plunger units driven by a Pump Crankshaft reciprocate through Pump Check Valve check valves to pressurize water to 2,500 psi at roughly 80 gallons per minute. The pressurized water travels down a thermoplastic Jet Hose to a rear-firing Jet Nozzle whose angled jets both propel the hose forward through the pipe and scour the walls. A Pressure Relief Valve valve dumps flow back to the tank if the nozzle blocks, protecting the pump.

Vacuum system and debris tank

The Vacuum System uses a positive-displacement Vacuum Blower to create the vacuum that lifts sludge and water into the tank. A Cyclone Separator separates heavy debris from the airflow, a Vacuum Filter protects the blower from fines, and a Blower Silencer cuts the exhaust noise. The recovered material collects in the Debris Tank, a Debris Tank Shell of about 2,000-gallon capacity with a full-diameter hydraulic Rear Door and Dump Cylinder units that tilt it for disposal. A Level Float Shutoff closes the vacuum inlet when the tank fills so sludge cannot reach the blower.

Boom, reels, and controls

The Vacuum Boom and Reels carries an articulating Vacuum Boom that positions the Vacuum Tube Set over a manhole or catch basin, plus a powered Jet Hose Reel driven by a Reel Motor that pays out and retrieves the jet hose. The Control System include a rear Control Panel showing pump pressure and tank level, a belt-pack Wireless Remote so an operator at the manhole can run the pump and reel, and a Pipe Inspection Camera for inspecting the pipe before and after cleaning.

Chassis systems and use

The Chassis Systems provide the road functions. The Air Brake System are dual-circuit air brakes with an engine-driven Air Compressor, Air Reservoir reservoirs, and S-cam Drum Brake units. The Suspension uses leaf-sprung front and tandem rear axles to carry the heavy tanks, and the Steering System is hydraulic power steering. In service, a crew positions the truck over an access point, lowers the vacuum boom, feeds the jet hose into the pipe, and works the nozzle upstream while the vacuum recovers the loosened material. When the debris tank fills, the crew dumps it at a disposal site and refills the clean water tank before resuming.