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RTG tyre pressure monitoring - a retrofit, not a rebuild
An RTG works on eight or sixteen tyres, and the machine's behaviour changes before a tyre fails. The problem is that nothing on the crane tells the operator which one is going soft. A retrofit puts that number in front of them without touching the crane's own controls.
What the retrofit actually adds
Two things, and neither of them is a change to the crane:
- One sensor per wheel position, on the valve, measuring pressure and temperature.
- One receiver on the machine, reporting the whole set of tyres over one interface — CAN, RS232, RS485 or Modbus RTU, chosen at the factory. It is one interface per unit, not four.
The crane's own controller keeps doing what it does. Our receiver is a node on the network or a serial device on a port; the crane decides what to do with the data.
Why RTG is a good fit for this
| Item | What it means on an RTG |
|---|---|
| Wheel count | 8 or 16 positions typical; the receiver covers up to 256, so one unit is enough with room to spare |
| Data cycle | 500 ms on the output side — fast enough to see a leak develop, slow enough that you are not paying for a constant stream |
| Sealing | IP68 on the 433.92 MHz sensor — a container terminal is a wet, dusty, salt-exposed environment |
| Pressure range | 0–1400 kPa gauge (100–1500 kPa absolute), accuracy ±7 kPa |
| Temperature | −40 to +125 °C — covers yard heat and brake/hub heat |
| Sensor mounting | Valve-mounted, so nothing is wired along the axle and nothing has to be dismantled to change a tyre |
Getting the data into the crane PLC
Three routes, in order of how often they are used:
- CAN — the receiver publishes the tyre set onto the crane's bus. If the crane already has a CAN node free, this is the shortest route. We work in 11-bit or 29-bit frames, fixed at the factory, and we have deployed J1939-format message sets in construction machinery integrations.
- Modbus RTU / RS485 — the receiver is a slave only: the crane PLC polls it. This is the usual route when the PLC has a spare serial port and nobody wants to touch the bus.
- RS232 — point-to-point into a serial port. Simplest electrically, and the option that needs the least from the crane's integrator.
For PROFINET terminals, the receiver's RS232 output goes through an RS232-to-PROFINET gateway; that gateway is a separate item, and it is worth naming it as such in the bill of materials.
The radio path is the real engineering problem
Steel is the constraint, not the number of tyres. A gantry is a large steel structure, and the tyre you care about may be on the far leg. Two practical rules from site work:
- Place the receiver by drawing, not by trial. Work out which tyres have line of sight and which do not, then put one repeater on the far side if needed.
- Do not hide the receiver behind a structural member just because the cable was shorter there.
What we need to quote it properly
- Crane type and tyre count (8 / 16 / other), and the tyre size.
- What the data has to reach: the crane PLC, a cabin display, or the terminal network.
- Which interface exists free today (CAN / serial / none).
- Whether this is one machine or a fleet — a fleet changes the receiver/repeater logistics, not the sensor.
With those we reply with the configuration, the frame layout and the repeater plan against your layout — in writing, before anything is ordered.
Send us the application
Tell us the application
Send the vehicle, wheel count and where the data must end up. We answer in writing.