Push-Rod Drain Camera

Overview

A push-rod drain camera puts an operator's eye inside a buried pipe. Where crawler tractors survey large sewer mains, the push system covers the small stuff, house laterals, stack drains, 50 to 225 mm lines full of traps and junctions a tractor cannot enter. The operator feeds a semi-rigid rod by hand, watches live video on a screen, and reads off the exact distance to every crack, root mass, belly, or displaced joint. A locating beacon then turns that on-screen distance into an X on the ground where excavation should start.

The system breaks into the Camera Head, the Push Rod and Reel holding 60 m of rod, the Control and Monitor Unit monitor/recorder, the Distance Counter, and the Locating Sonde, all carried on a protective Frame and Cage.

The push rod

The Push Rod is the component that defines the tool. It is a fiberglass-reinforced rod about 9 mm in diameter with the video and power conductors running up its core and a slick polypropylene jacket outside. Its stiffness is a deliberate compromise: rigid enough in column to transmit a push 60 m down a pipe with friction at every bend, yet flexible enough to follow a 90° elbow in a 50 mm line. Push too hard against a blockage and the rod buckles into a loop inside the pipe, the operator learns to feel the difference between the head advancing and the rod folding.

The rod lives coiled on the Reel Drum, which spins on Ball Bearings as rod pays out through the Rod Guide. A Slip Ring at the hub carries signal and power across the rotating joint, so the drum turns freely without twisting the cable to the monitor. The Drum Brake keeps the drum from overrunning and birdnesting when the operator pulls rod off quickly.

The camera head

The Head Housing is a machined stainless capsule about 25 mm in diameter, sealed by O-Ring Sets to IP68, it works submerged in sewage and survives being dragged over broken pipe edges. Behind a Sapphire Window sit the Lens Assembly and a CMOS CMOS Image Sensor; the wide-angle fixed-focus optic keeps everything from the near pipe wall to several metres ahead acceptably sharp. The head is self-leveling: the sensor package is pendulum-mounted inside the capsule so the picture stays upright no matter how the rod rolls, which matters because defect reports reference clock positions ("crack at 3 o'clock").

Pipes are dark, so a LED Ring Array rings the lens. The LEDs dim from the Control Keypad, full power in a 225 mm concrete line, a fraction of it in white 50 mm PVC, where glare would wash the image out. A Flexible Spring Neck couples the head to the rod, bending through traps that would stop a rigid joint, and clip-on Skid Shoes center the head in larger pipes while keeping the lens up out of silt.

Finding the defect from the surface

Video alone tells you what is wrong; the survey is only useful if it also says where. Two systems answer that. The Distance Counter presses a sprung Counter Wheel against the rod at the reel exit; an Encoder converts wheel rotation to payout distance, accurate to about 1%, and the Control and Monitor Unit overlays the figure on the recorded video. The operator zeroes the counter at the access point, so every observation is logged as a distance down the line.

Distance along a pipe of unknown routing still does not give a dig location, which is the Locating Sonde's job. Threaded between rod and head, it drives a Copper Winding around a Ferrite Core core at 512 Hz, a frequency chosen because it penetrates soil and even cast iron pipe. With the head parked at the defect, a surface receiver sweeps the ground and nulls onto the peak field directly above the capsule, typically resolving position and depth to within centimetres at depths up to 5 m.

Recording and reporting

The Control and Monitor Unit packages a 9-inch daylight-readable LCD Panel, a Compute SoC Module that encodes 1080p video to MP4 on the SD Card Slot card, and a microphone path for spoken annotation played back through the Speaker. Text overlay from the keypad stamps the client name, pipe size, and material onto the footage. Drain condition reporting follows coding standards, EN 13508-2 in Europe, NASSCO PACP in North America, and the timestamped, distance-stamped video is the evidence behind each coded observation. A 2S2P Li-ion Cell, 18650 pack managed by a BMS Board runs the system for about six hours, covering a full day of residential surveys between charges.