It’s one thing to get used to battery-powered locomotives like UP is exploring, but this article about trucks on German highways using catenary is another thing altogether.
GM proposed this for trucks circa 1949… complete with piggyback communications and control at higher frequency over the powerline.
As with railroad electrification, cost is the first hurdle, first to install and care for the wire, and second to build or modify enough equipment to make use of it.
The truck-boosting system I did in the late '70s used catenary, with the semiautonomous vehicles intended to ‘snap’ trucks on upgrades and dynamically brake them on downgrades. It is much easier and ‘feature-rich’ to do this today, especially in the transition to “electric trucks” and the lower levels of autonomous functionality.
It was done with buses. Rubber tired streetcars, basically. Dual catenary, since there was no return to ground through the rails.
Granted, it was limited geography.
Perhaps the concept could be combined with batteries. Instead of running catenary for miles and miles, there could be intermittent stretches, as defined by expected battery life, etc, where the trucks could pick up a charge “on the go.”
Yeah, San Francisco and Seattle employ this for a large portion of their bus fleet. It’s the upfront costs, just like rail.
Like NYC and Pennsy filled passenger train tenders with water on the fly? Wonder if freights ever did that, too?
A number of cities had ‘trackless trolleys’. For a while Baltimore was operating both tracked and trackless trolleys. Each type of vehicle operated their own routes that were separate from each other.
A Pan instead of trolly poles. How is the Pan designed so it never causes a short circuit if one side conductor of pan touches both wires ?. If that proves out then maybe future RR installations could use that being able to get full 3 phase AC by the 2 wires and rail for third? Was that how the electrification of cascade tunnel was done ?
Buses don’t use pans: they have to swing either side of the wire location. Poles are necessary; a system from England actually has multiple pickups for separate current and ground wires in a special head… which is out on the end of a swiveling pole arrangement…
Most bus systems used trolley wire instead of catenary; you can use cat with a pole if all the pulloffs are above the flanges of the wheels (or shoes) of the pickup, the pole can track the wear-distributing ‘wiggle’ of properly-implemented cat, etc. Trolleybuses are rubber-tired and can have a much softer and more compliant suspension than a rail vehicle, hence no need for all the extra copper, support, and care to keep the actual trolley wire level with the track to avoid contact problems.
Early three-phase locomotives had two pans and two separate trolley wires/cats. The pans were designed so they would never short a different connection in service. You might do this with a BRT in a very restrictive guideway, but there are limits to how you keep shoe wear minimized while ensuring no phase-to-phase shorting…
The truck systems I have seen appear to be only for ‘highway lane’ service with minimal off-lane drift; they have a large wide insulated head on a pantograph which has two contact zones for the wires necessary. I suspect the ‘sensors’ involved will keep the truck properly in lane under the wires regardless of road or wind shock, etc.
In my opinion this is a reasonable ‘dual-mode-lite’ conversion for trucks with hybrid power trains but limited on-board battery capacity that operate on routes with known severe grades, with only the up-and downhill grade portions being wired at first.
I was trying to find how the single pan worked for the truck.
Here is the American experimental version. Note the pantograph and overhead-wire detail:
In this version the truck is a parallel hybrid, with onboard power that keeps its systems running properly if for any reason the overhead power is interrupted or needs to be disabled. It is possible that modern ‘anti-idling’ APUs could provide the necessary power for this and allow the truck’s prime mover to be shut down, as the Times story seems to indicate, with full prelubing and hot start, etc. as desired.
Trucks shown appear to be two wire pantograph equipped.
That is correct. Only limited off-axis capability while on wire. Internal or stored power, including from glorified APU, at other times.
Yes, this could be arranged for any split of traction and charging power when running, and is fully suitable to be used ‘interrupted’ as in dual-mode-lite, or to give additional boosting/regenerative braking on inclines…
note the two wires are definitely farther apart than normal trolly wires for electric buses. As well the pan pick up sections appear narrow enough to prevent any shorting by the pan to the two feeders.
Two relatively widely spaced wires for two of the phases with the rails as the third phase. Current collection was via trolley poles.
FWIW, the Bay Area Rapid Transit District had done a fair amount of research into power for the BART system, with a contract to Ohio Brass investigating three phase power via three relatively closely spaced conductor rails. I ran across this tidbit when browsing the transportaion engineering library at Cal.