Throttle is to slow down, but full throttle is max speed?

Question

According to Merriam-Webster, to throttle means to regulate the speed via a constricting valve, especially to speed down.

For example, "to regulate and especially to reduce the speed of (something, such as an engine) by such means".

When someone says, throttle this, in my experience they mean, restrict it, slow it.

So "full throttle" to me, would mean "to slow down as much as possible", "to fully restrict".

But it seems it means the opposite, "maximum speed".

Can anyone explain to me this contradction?

Answer 1

Full throttle or wide open throttle means the throttle is fully open, allowing as much air and fuel as possible to the engine, and hence producing as much power as possible. (Wikipedia: Wide open throttle.) It's like a door. If it's wide open, lots of people can go through, if it's nearly closed it's hard to get anything through.

To throttle means to regulate power using a throttle, usually but not always by partially closing the throttle and reducing the amount of air and fuel reaching the engine. (Wikipedia: Throttle). If you think of full throttle as the default state, then any change to the throttle will be to reduce power. You can throttle up or throttle down to increase or decrease the flow to the engine and hence often increase or decrease the speed: (See this question about "throttle up".)

Answer 2

To quote Neil, 'This illustrates [a typical] case where the meaning of language subtly shifts over decades of usage.'

The Online Etymological Dictionary gives the sequencing of the appearance of each usage in the English lexis [reformatted and otherwise adjusted slightly here]:

• throat (n.): Old English [pre Norman Conquest] þrote

• throat (v.) was used in the late 14c. to mean "cut the throat of, kill by cutting the throat"

• throttle (v.): "strangle to death," c. 1400, probably from Middle English throte "throat" (see throat) + -le [possibly just to distinguish it from the preceding verb]

• throttle (n.) 1540s, "throat;" it appears to be an independent formation from throat, perhaps a diminutive form, not derived directly from the verb. The mechanical sense is first recorded 1872, short for throttle-valve (1824). Full-throttle (allowing maximum speed) is from 1848 in reference to steam engines.

So the verb always had the strangulation sense, while the noun merely refers (literally, but most often figuratively) just to an actual throat, more broadly an orifice, with no reference to constriction/restriction. So throttle back retains the sense of constriction/limitation the verb has, while at full throttle with the noun means with fully open throttle.

Answer 3

This illustrates the case where the meaning of language subtly shifts over decades of usage.

Let's start with the verb 'to throttle', meaning restrict. This action was needed to control the speed of internal combustion engines, to control the speed, by 'throttling' the supply of air and fuel to it.

When the person using the term is designing the car, or mending the engine, it's this verb form that's uppermost in their mind.

To the user of the car, not needing to know any of the details of an engine, sitting facing a range of controls (the brake, the clutch, the throttle), throttle is a noun, the name of the control.

The default state of a car is the engine running at idle. To make it do something useful, you have to 'give it some throttle'. To make it go as fast as it can, you give it 'full throttle'.

This is reinforced by the fact that, in a car, you have a choice between two pedals. You have the brake, which slows the car down, and the throttle, which obviously does the opposite thing.

Concentrating on the throttle pedal, it is spring-loaded in the low-speed direction. To make the car go faster, you press harder on the throttle, you give it more throttle.

The original verb form retains its sense of operation direction. The noun form appears to have lost that sense. When we say 'throttle it up', we are not even using the original verb form, but a new verb based on the noun, use the throttle control to so as to increase the speed.

Answer 4

This is my first go at this (as a native British English speaker)! I'm not a linguist either and my school days were many decades ago but here goes...

You say "Throttle is to slow down, but full throttle is max speed?" Well, by the first word, "Throttle", you are referring to the verb "to throttle" which means to restrict in some way. We're all in agreement there I think?

"full throttle" refers to an adjective and a noun, which, from the days of early petrol engines, forms a part of the carburettor (the Venturi and the butterfly valve). The butterfly valve, connected by a cable to the accelerator pedal, when fully open, allows maximum air into the carb. which mixes with more petrol which produces more power. So "full throttle" became an abbreviation of "a fully open throttle".

So it is essentially the difference between using the word as a verb and as a noun. The verb is as you expect. The noun, because it became an actual component of an engine, is treated differently due to the associated butterfly valve.

Answer 5

To throttle means to reduce the diameter of, to restrict. Thus, we even say “I was so upset, I could have throttled him,” where throttle means to strangle (reduce the effective diameter of his windpipe)… obviously used figuratively in that context.

The throttle on an engine is a valve or mechanism for controlling the fuel supplied. Thus full throttle means with the supply wide open, so with no restriction. And to throttle back means to reduce the fuel flow, and thus the power, speed, or (metaphorically) the intensity of a thing. It should be heard as meaning to adjust the throttle in the direction of reduced throughput, and in that sense is analogous to dial back: both throttles and dials can be used to either increase or decrease a quantity, so the adverb back means in the direction to decrease the quantity.

In any event, though we might wish that languages were 100% rational and consistent, they aren’t. Consider that Get up from that chair! and Get down from that chair! both mean stand up (with different connotations, to be sure). If English were consistent, we might expect throttle not to mean strangle. But then we might not expect kneecap to mean break someone’s kneecaps either.

Answer 6

A throttle is a device that determines how much power a system produces. Full throttle means the system is producing as much power as possible.

The (probably) oldest version of this is a steam-ship or steam locomotive, where the boiler constantly produces steam and the throttle controls how much steam is allowed to enter the pistons or turbines that convert the steam power into motion. "Full throttle" in this case means the throttle is set wide-open, allowing as much steam as possible to enter the propulsion system. (On many ships, full throttle actually isn't as far open as the system can go; in this case they have a setting for "Flank" speed, which is actually as wide as the throttle can go, but can only be used for a short time without damaging the engines due to the stress involved. In this case 'flank' refers to the military maneuver of flanking: to attack from the sides or back of an opposing force to strike at their weakest points. You would use flank speed to get a sudden burst of extra propulsion to get into an unexpected position.)

Internal combustion engines, jets, and rockets have a similar situation, but in that case the throttle controls how much fuel enters the combustion chamber. At "full throttle", the system is introducing as much fuel as possible, producing the maximum possible energy output. On a car, the accelerator/gas pedal is the throttle (more or less -- in today's computer-mediated control systems, they're not exactly identical), but on an airplane it's a lever that's pushed forward to increase power or pulled back to reduce the power.

In internet terms, we sometimes talk about "getting throttled", which means the throughput is being reduced from its normal state. That's a metaphor to the physical device, with the implication that you're normally at full throttle, transmitting information as fast as possible, but server between the two endpoints may decide to intentionally limit your communication to more evenly distribute capacity among all the users (or to artificially slow down your connection for more nefarious reasons).

The use of the term 'throttle' to mean "reduce a flow" is much older than the internet; 'throttle' is also a synonym for 'choke' in that sense, as in "He grabbed the man by the neck and throttled him", which draws a metaphor between hands closing off the victim's airway and the throttle on an engine cutting off the flow of steam (or fuel) to the engine.