What does it mean for a truck to be "governed to increase efficiency"? We saw a truck today that had a big label on the back proudly proclaiming that it was that but we have no idea what it means and web searches are only telling us that it has something to do with speed
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@Felthry In vehicular terms governing does has to do with speed limiting; so the truck COULD go faster but the engine control module is set up to prevent the truck from accelerating past a certain point (at least through the accelerator; it can still go faster simply through gravity and inertia)
Basically, it either means that an onboard computer adjusts the engine's RPMs while the vehicle is moving, but staying at a relatively consistent speed, to maximize fuel consumption... or a speed limiter is being used that will not let the vehicle accelerate beyond a maximum set speed... or both.
@JulieSqveakaroo the first one of those is what every automatic transmission ever does though
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No.
An automatic transmission just automatically changes gears when the torqve of the engine reaches a designated speed, with some slip for acceleration and deceleration.
A computer controlled and monitored engine works beyond that and lowers RPMs and other smaller things like fuel flow and idle speeds, completely independant of the engine torqve.
@JulieSqveakaroo Hydraulic automatic transmissions maybe change gears based on torque and speed, but I'm pretty sure most modern cars do a lot more than that--certainly ones that have a CVT would need to, right?
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The transmission of any car, old or new, is only involved with changing gears. Adjusting RPM is a completely separate thing that the driver does with the throttle/accelerator.
Essentially, the onboard computer controller is just adjusting a little bit plus or minus on how far down the driver has the accelerator.
I'm saying that the truck is not changing gears when any of this is happening, and I'm sorry if I'm not being clear on that.
@JulieSqveakaroo I thought changing RPM while maintaining the same speed necessarily meant changing gears?
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Under normal operation, from a starting stand-still, a car will accelerate up through... roughly 3500 RPMs before shifting up into 2nd gear on an automatic, and then though the car is still going at the same speed, the RPMs drop to right around 2000 due to the changes in the gear ratio, and this pattern keeps happening as gears continue to climb up.
These numbers are NOT AT ALL absolute, and vary highly between cars and models, but this is the basics of what happens when cars shift up gears.
@JulieSqveakaroo Yes, that's what I'm saying--when speed stays the same and engine RPM changes, that's gear shifting
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This is not a drastic or even noticeable change. This is maybe dropping the RPMs down 100 or 200 revolutions or so, and purely to maximize fuel consumption.
That isn't enough of a change for the gears to shift.
@JulieSqveakaroo But how does it do that without changing the speed the wheels are turning?
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Ok... have you ever driven a manual car?
Ok.
In a manual car, while you're cruising along, you can take your foot off the accelerator and hold down the clutch pedal, effectively putting the car into neutral and coast along, slowly losing speed unless you're on a downhill or something, and during this time because you're not actively on the gas, your RPMs drop down to idling speeds of around 1000.
@JulieSqveakaroo Okay, so you're saying the governor thing acts as a clutch?
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Well... sort of.
If the vehicle is going up a hill or the driver intentionally accelerates and needs the torqve, then the computer doesn't change things at all.
But during any low-torqve cruising, this qvietly kicks in in the background... and it's not the full neutral (because coming out of that is actually potentially damaging to the transmission)... but just lower RPMs to save some gas.
Essentially, this is what's happening, but the computer is controlling that coasting.
If the computer detects that the car is maintaining speed but the torqve of the engine isn't reqvired to keep that speed, it overrides the gas pedal qvietly and makes the truck be in a state of semi-idle. That is what I mean by the RPMs are reduced.
Nope.
RPMs, Revolutions Per Minute, is just how fast the main shaft connected to the pistons is turning. That connects to the gearing of the transmission, manual or automatic, and the differences in sizes and teeth of those gears as they connect to the main shaft changes the overall torqve and potential speed-output of the vehicle...
@Felthry it just means that it has a speed governor to limit the max speed. its probably more to stop truckers from going as fast as they can (cuz thats something they used to do)
@Felthry a speed governor will limit the top speed, driving slower is generally more efficient