The early days of any new technology are full of early-installment weirdness. Smartphones used to have physical keyboards, television once used 60-line broadcasts, and automatic transmission-equipped cars didn’t always let you throw it in a shifter position called park. Say what?
It should go without saying that using a car’s parking brake to lock some of its wheels while parked is a good idea. After all, these beefy mechanical systems should stop two tons of metal and glass from wandering off to tour the local estuaries, do some landscaping, or get into other mischief. However, redundancy is important in any safety system, so it’s best to not trust the parking brake alone. [Editor’s Note: I once had my stickshift Jeep XJ’s park brake “let go” on what I thought was flat ground. It wasn’t. I walked out of my friend’s house and found my Jeep in the neighbor’s yard. -DT].
Whereas leaving a manual gearbox in gear directly connects the drive wheels with the engine to prevent vehicle movement using the engine’s compression, conventional hydraulic automatic transmissions use a fluid coupling to connect the crankshaft to the transmission’s input shaft, so they’re not rigidly connected, meaning they need an extra bit of hardware to lock the drive wheels. That’s where the parking pawl comes in. It’s a sturdy piece of metal that locks into a toothed wheel on the transmission’s output shaft, stopping the drive wheels from rotating. These pawls are typically the most robust things in automatic transmissions, so they’re unlikely to break. However, engaging the parking pawl wasn’t always as simple as throwing the gear selector into park.
While early Hydramatic transmissions did feature a parking pawl, operation isn’t exactly intuitive by modern standards. See, the parking pawl on these transmissions only engages with the gear selector in reverse and the engine off. Sure, some owners of modern high-performance cars with weird gear selectors would figure this cached parking position out, but without a dedicated park position on the shifter, locking the output shaft of an early Hydramatic seems like a needlessly obfuscated process. For a conventional automatic transmission with a dedicated park position on its shifter, we need to jump forward eight model years from the launch of the Hydramatic to the 1948 Buick with its available all-Buick Dynaflow automatic transmission, referred to in a period brochure as having “the first positive parking lock ever provided in a liquid-coupled drive.”
By modern standards, the Dynaflow two-speed automatic was a weird transmission, seeing as it started in its high-range direct drive ratio and used its torque converter to creep off the line. The resulting effect was the aural monotony of a car with a continuously variable transmission but without any of the CVT efficiency. You could lock the Dynaflow in first until about 60 mph or until enough valve float to un-sink the Edmund Fitzgerald is achieved, but we aren’t exactly talking about the pinnacle of sportiness here. The Dynaflow is rudimentary technology from a time when “treadle” was an acceptable word to use for “pedal” in automotive marketing materials.
Still, sprouting from the steering column of Dynafl0w-equipped vehicles was a gear indicator, and it read PNDLR. At last, a separate, distinct single-purpose parking pawl setting for automatic transmissions! Now that’s an innovation we can all get behind.
An honorable mention goes to Packard coming out with its Ultramatic automatic transmission of 1949. While it still didn’t automatically shift between low and high ratios, it featured a dedicated parking gear and a locking torque converter, the latter feature improving drivability substantially over Buick’s Dynaflow.
As a period Packard ad claimed, “You’ll never be annoyed by jerking or clunking, or “racing engine sensation”…never bothered by gas-wasting slippage at cruising speeds…never “outsmarted” by complicated automatic controls.” That certainly seems like a great leap forward from other automatic transmissions of the time with non-locking torque converters. As for the shift pattern on this bad boy, how does PNHLR sound? Having an “H” for high gear and reverse way down low on the selector totally isn’t strange, right?
Alright, so this was still the early days of the hydraulic automatic transmission, but wacky shift patterns would soon be fixed by Ford with the Fordomatic Drive automatic transmission, and the rest, as they say, is history. Today, throwing an automatic transmission in park is a no-brainer, but it took years for automakers to figure that out. Let’s be thankful this took less time than figuring out the modern pedal arrangement of throttle on the right, brake in the middle, and clutch on the left if so equipped.
A programming Note: This is The Autopian’s first installment of Invention Hour, where we talk about various car inventions, as well as fun car features and also odd failure modes.
(Photo credits: Buick, Packard, Ford)
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“Whereas leaving a manual gearbox in gear directly connects the drive wheels with the engine to prevent vehicle movement using the engine’s compression”
If that were true wouldn’t cars start to move as the compression leaked out? Also compression works both ways, cylinders ATDC will work against cylinders BTDC, more so in cylinders that just combusted.
Therefore I submit stiction is the greater demotivator here.
From my experience with my old Ranger, which had a 5-speed manual and 4.10 final drive, parking on a hill entirely depends on stiction. My childhood home’s steep driveway was too steep for the truck to hold; it would do a creep… Bump! All the way down until the truck was halfway into the street. Reverse would usually hold, owing to its shorter gearing, but low range was the best way to make sure it stayed put.
Ohhhh, so Park in an auto is the equivalent of leaving a normal car in gear (eg, on a hill). For years I’ve wondered why autos have park and a handbrake.
Fun fact – always use your parking brake! If you’re parked, in park, without the brake engaged, someone hits your car, breaks your pawl, and your car rolls into something you can be found liable! If your parking brake was engaged you won’t be.
If I ever drive an automatic again, I’ll try and remember that, once I remember to stop hitting the brake every time I want to change gear…
I kick the dead pedal just about every time I start my wife’s car.
If someone hits a modern car hard enough to break the pawl in the transmission I’d think the resulting damage would keep that car from going anywhere anyway.
Driving a Straight 8 Buick with a Dynaflow is a very unique and I might add pleasurable experience.
Early autos had different variations of the placement of gears. Like these examples with R at the very bottom.
What was the first car to use the ubiquitous PRNDL with reverse between Park and Neutral?
“Today, throwing an automatic transmission in park is a no-brainer…”
Anton Yelchin would like to have a word…
🙁
The Variomatic selector in my Volvo 66 GL embodies a rather different approach. It appears to have a park position but it does not:
https://live.staticflickr.com/65535/53268579949_d620940032_c.jpg
The selector, by design, has only three positions: reverse, neutral, and drive. The transmission itself does not have any type of park function whatsoever. The P marking exists simply to make the whole thing look more “conventional.” Even worse, the positions of the letters do not correspond to the locations of the functions. In the photo above it is in reverse, despite the lever being next to the letter P. Neutral is about where R is and drive is more or less at N. The lever does not move far enough rearward to reach D. This is very much not due to improper adjustment or breakage, this really is how it is supposed to be.
The owner’s manual handles this discrepancy via the sin of omission, simply treating the P marking as if it doesn’t exist, showing only a mysteriously empty box above R in the shift diagram without any further comment in the text:
https://live.staticflickr.com/65535/53268580079_5b590d83ae_c.jpg
.
Now this makes sense:
“Volvo produced roughly 106,000 units of both the saloon and estate 66, and no more than 14,000 were sold in the United Kingdom. The majority were sold in continental Europe rather than in Sweden, where the car was never accepted by Volvo buyers”
https://en.m.wikipedia.org/wiki/Volvo_66
And yet, of the two estates and one sedan known to be in the US, all three are RHD examples from the UK. (There are other examples of the DAF 66 in the US, of course, but as far as the DAF club knows, only three of the Volvo-badged versions.)
GM still has a mechanical pawl in the Bolt instead of relying on electrical parking brakes.
There’s a video from Munro about it, I think it was on the old lighting site.
I had a ’64 Corvair with the 2-speed Powerglide with no park, just RNDL on the selector. There was a big handle under the dash to set the parking brake, but it was almost useless on a hill, so I always carried a cement block as a wheel chock.
I have the same setup, but my parking brake works
My parking brake worked, but IMHO it was pretty weak on hills.
Mom had a ’63 – and yes, she and Dad tell me that’s how it was.
If you parked on a hill, you understood why you needed to “curb your wheels” (which back then meant to turn your front wheels to the curb – not at all what it means with todays low-profile tires and oversized wheels)
How the heck does that work? You park on a hill, keep your foot on the brake, and do a yoga position from Hell trying to heave a cement block behind your tire before the car rolls away?
I love Corvairs (bucket list car for sure), and I don’t mind automatics, but a two-speed anything already seems a bit restrictive (my three-speed T-bird felt like it didn’t have enough gears already), and now you tell me they don’t even have park? Man, if I ever do end up shopping for a Corvair, it’ll just have to be a manual I guess. Those automatics sound awful.
You could use the parking brake and “curb the wheels” as said above, but I always thought it was too weak to leave on a hill without an extra chock.
You couldn’t go faster than 100mph in a ’59-’64 as the front acted like a crude lifting body, and the front wheels got really light.
They’re fine, the Powerglide has always been a very robust transmission, just gets a bit noisy over 70mph or so, but that’s supposedly normal. FWIW, the manuals are slightly more likely to throw fan belts, but that’s less of an issue across the board in general with modern belts, probably not a serious issue in a non-turbo car
Fun fact: ~30 years ago, some hard drives supported the use of a DOS command called ‘park’. Running the command would tell the drive’s firmware and hardware to move the read/write head away from the disk and hold it in place; the user could then turn the machine off.
Most consumer drives are now solid-state, but back then they were made of rotating platters and the read/write head was on an arm that moved back and forth, much like the arm of a record player moving over a record. And do you know what material was on those disk platters?
Iron oxide. Rust. 🙂
Major Pedantic to the rescue! The form of iron oxide on spinning drives is not technically rust. Rust (red iron oxide) is Fe2O3. Magnetite (black iron oxide) is Fe3O4.
Thank you, mysterious stranger!
I mean, uh, shut up. 😉
Ahem. Technically what’s called “rust” may consist of a number of different ferric oxides, almost always hydrogen-bearing, either as a hydrous (Fe2O3·nH2O) or as a hydroxide (e.g. FeO(OH) or Fe(OH)3) compound, frequently together in combination.
It may have taken 32 years but I knew my background in Mössbauer spectroscopy would come in handy some day!
Edit: Huh. Subscripts are not supported.
Well of course! But none of them are magnetite, which was my main point. But I respect your uber-pedantic addition to the conversation! As an analytical chemist, I respect and welcome all types of analytical techniques.
Mostly I just wouldn’t want a certain editor-in-chief and co-founder to think that rust isn’t shown proper consideration in the comments.
“As an analytical chemist, I respect and welcome all types of analytical techniques.”
Ditto! The weirder and more obscure the better!
What’s one iron and one oxygen between friends?
Wüstite.
If we’re being pedantic: hard drives haven’t actually used magnetite in close to two decades. They switched to a variety of cobalt alloys like cobalt-iron or cobalt-chromium-platinum, plus other layers and variants (that tend to be trade secrets, so no idea on the details for current stuff).
Park was used or encouraged when moving the device.
Well yeah. Heads actually touching platters was…not good.
“Today, throwing an automatic transmission in park is a no-brainer…”
You sure about that?
Strangest trend in the auto industry is EVERY manufacturer wanting to reimagine shifters in their own way that is so wildly unintuitive we had to have the cars place themselves in park to prevent injuries.
It does get tiring as it seems like every car I get into these days has a different way to shift into gear.
It’s all about cost savings. Interior layout space for the driver is at a premium from a design perspective, so Console shifters are a no-go unless it’s an enthusiast vehicle. Column shifters work but are considered cheap and dated (I personally disagree with this notion, but it comes down to a historical bias imo). A linkage or cable is no longer required, so Mechatronics on the transmission only require a signal to actuate different drive modes. These various signal transmitters can come in various small shapes, but OEM is going to spec the cheapest switch that satisfies customer quality and FMVSS requirements.
“As for the shift pattern on this bad boy, how does PNHLR sound?”
My brain, immediately: PUT IT IN H!!!
https://youtu.be/9HXT7fDkf9I?si=9q2V_WkwYMHzKuUV
Beat me to it!
Put it in H!
https://media3.giphy.com/media/v1.Y2lkPTc5MGI3NjExZHlraGg1ZGNmejJ3d3EwaWtuZHp0NTl1eGd6dGRkbmdrbng0b3R3ZSZlcD12MV9pbnRlcm5hbF9naWZfYnlfaWQmY3Q9Zw/l2JdUDefK3hFqbFPq/giphy.gif
“These pawls are typically the most robust things in automatic transmissions, so they’re unlikely to break.”
Actually, it’s pretty easy, barely an inconvenience. Just throw it into Park while moving.
My dad has repeatedly told me a story of when he and his brother were teenagers and accidently tried that. This was around New Orleans in the mid 60’s. His brother daily drove a manual Dodge, but on this night where they were together out trolling around town, they were driving Mom’s new Chrysler (I don’t know which model). They revved on some guys and got in to a street race, but it didn’t last all that long. My uncle laid in to the gas pedal and as the revs climbed, he forgot which car he was driving and went to shift to the next gear. But since this was an automatic, he instead slammed one foot hard on to the brake pedal (instead of the expected clutch pedal) and with the other hand rammed the transmission in to Park. My uncle had hit the brake pedal so hard the tires locked up and they slid to a halt. After laughing at their stupidity, my uncle cautiously put the car back in to gear to see what happened. It went right in to gear and they went about their night. Because he had locked up the brakes right as he went to shift, there was no load on the transmission from the tires. They narrowly avoided completely destroying Mom’s new car, but they got away with it. I’m not sure my grandmother ever heard that story before she passed away. I think they buried that one :D.
In my case it was on purpose and a desperation move. I was driving my brother-in-law’s second car, a 60’s Ford Galaxy (this was in the 90s) as mine was in the shop. Driving along a Sunday morning to meet some friends for breakfast, I was coming to a light. The brakes were really grabby, so I started early with some light pressure – but this time no grabbing. Then I pushed harder – and then to the floor – nothing. As I was headed for a red light I needed to try something to slow down, and the parking brake also did nothing, so I threw it into Park. The car never hesitated for an instant. I started to turn into a gas station on the corner rather than go through the intersection, and then the car stalled, killing the power steering. So now I was faced with driving into the pumps! I managed to wrestle the steering around the pumps and get the car behind the station into an empty field where it finally came to a stop.
We tried that in my friends old 85 300D back in high school. It wouldn’t go into park at 55, so there must have been a lockout. It would go into L at 55, which made the engine very unhappy, but you can’t kill an old Benz that easily.
Throwing it into drive is tight!
Someone got it…
Sort-of related: once as a new driver I parked on a hill and put it in Park without first setting the emergency brake; it locked up, and it took a gang of us to push the car far enough uphill to relieve pressure against the gear before we could get it back into N (or D or R or whatever we did). Thirty years later, I still set the E-brake in N before parking. Do I need to do this in modern cars? I’m afraid to test it in my funtodrive2020hondacrv, but has technology changed?
I can’t confidently state that 98+ percent of modern automatic drivers just put it in P and probably haven’t so much as ever touched their parking brake, except maybe clipping the edge of the handle with their coffee cup
I mean, they seem to hold up well enough, but i too as a habit, whether it be mine or the gf’s, ill set the p brake then into park. Took a demonstration to her on a hill as to why i do that, and now shes starting to do it
Put it in “H”!
Interesting article and a gorgeous wagon parked at the top of the page. Looking forward to this shift in coverage with Invention Hour and getting in gear with new discoveries. I’ll automatically go to the next article in this series!
Buicks of that era were basically rolling sculpture, very elegant
This article casts a pawl over the history of auto transmissions. I like it.
I’m just going to park myself here and watch the pun replies come in.
I’d remain neutral on the subject if I hadn’t had some “fun” in the past (see above).
We’ve hit a new low in the comments.
If only we could…filter them.
FUCK I’ve been reminded of the existence of late 40s Roadmasters. I’d make mine a ’49, But God damn they’re so sick. If only I had a need or the space for a 75 year old hunk of American wood and steel. 🙁
’49 Roadmaster is best Roadmaster. I can’t find a video of it anywhere, but I remember Jay Leno doing a routine referencing this model, talking about how awesome it was to know the person in front of you was looking in their rearview mirror and seeing nothing but a row of huge, gleaming chrome teeth. And also about how cars in those days didn’t even have padded dashes, let alone seatbelts. If you got into a wreck, they just hosed it out and sold it to the next guy 😀
Definitely know this car. It’s a 1949 Buick Roadmaster. Straight-8, Fireball-8. Only 8095 production models. Dad lets me drive slow on the driveway, but not on Monday. Definitely not on Monday.
I’m definitely not wearing my underwear.