The Clark CT-30 or “Clarktor” is hardly a marvel of engineering, and yet it continues to trudge on day-in and day-out, yanking luggage at airports around the world. Short, roofless, and with a thick steel plate on its face, the Clarktor is a unique and charming-looking machine, and it turns out it is way, way older than you think. It’s not only a World War II veteran, it actually hails from before the Great Depression.
While at the LAX airport on my way to Vancouver, I couldn’t help but take some photos of some luggage-tugs, and as I went to post them to Instagram, I realized that I knew very, very little about these little machines.
So I did some digging, and what I realized is that these things are truly ancient.
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The company that first made those baggage tugs (or towing tractors, or simply “tugs”) is Clark, and like many vehicular outfits in the U.S., it started in Michigan:
From day one, Clark was an industrial machinery company, building the “world’s first internal combustion-powered industrial truck” known as the Tructractor. As you can see in the image above, it was a rear-engine, rear-wheel drive, rear-seat, front-bed flatbed truck.
And believe it or not, only ten years later came the first Clarktor, and it looked much like the luggage tug we all know and love. Yes, in 1927 — almost 100 years ago!:
Clark Material Handling Company, which now makes mostly Forklifts, describes the first Clarktor, writing:
The Clarktor tow tractor is introduced. The Clarktor was used to pull airplanes and warehouse trailer trains. It was equipped with an electric self-starter, the first industrial truck or tractor to have this feature as standard equipment. The Clarktor remained in production until 1987.
As far as I can tell, Clarktor towing tractors really became prominent in the airline world sometime around World War II. The Delta Museum describes what was (and may still be) the company’s oldest bit of GSE (Ground Support Equipment, though the Delta Museum calls it “service equipment”):
This 1940s Clark “Clarktor” baggage tug was the oldest piece of ground service equipment owned by Delta Air Lines when it was restored in 1990.
The tug was purchased from the U.S. Department of Navy by Northeast Airlines in December 1961, for $5,000, and came to Delta when two airlines merged in 1972. It spent most of its life at New York-LaGuardia airport, and finally at Denver airport until late July 1989. At the time of its restoration, it had been overhauled five times and traveled over 53,000 miles.
The World War II-era Clarktor was the “Clarktor CT-6.” You can see one tugging munitions here on the bottom left during the Korean War efforts. Here’s the caption from the U.S. Air Force:
Major Murrit H. Davis, Commander of the 39th Fighter-Interceptor Squadron in “Sexy Sally II” and another F-51 of the 18th Fighter-Bomber Wing (probably piloted by Captain Alphonzo T. Wagner), make a successful low-level napalm run over P’yongyang, north Korea on the morning of 14 August 1951. In this famous photograph from the Korean War, two napalm fire bombs head towards their targets just a split second after being released from shackles beneath Sexy Sally’s wing. Maj Murrit was killed in action that day flying F-51D 44-74035 while searching for two other pilots shot down on the Pyongyang mission. His remains have not been recovered. (Caption adapted from original at Truckbusters from Dogpatch, USAF photo)
And here’s a restored 1943 model:
The CT-6 above was for sale in the Netherlands; here’s a clip of it driving around:
These things made it all around the world. Here’s an online forum of people from Belgium, the UK, the Netherlands, Australia, and New Zealand talking about their Clark CT-6 tugs, all of which undoubtedly were transported by the U.S. during World War II.
Someone named John Norris wrote a great history of the Clarktor CT-6 on a site named Military Trader Vehicles. Here are a few quotes describing Clark’s involvement in World War II:
As early as 1941, the Clark company was already producing around 90 percent of the military requirement for heavy-lift equipment, including forklift trucks and tow tractors. By the end of the war in 1945, it was said that there was not an Allied airfield in America, Britain or Europe which did not have a Clark vehicle on it. Throughout the war the company continued to produce new cargo handling vehicles, such as the “Planeloader” in 1943. This was the first purpose-built forklift designed specifically for use by the military in remote locations where the terrain was rough and temperatures could be extreme. These would more than prove their worth on the airfields constructed by the US Naval Construction units, known as “Seabees”, on the remote islands across the Pacific during the “Island Hopping” campaign.
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The “Clarktor 6” was … known for its compact size and was developed for use on airfields as an aircraft tug. The Clarktor 6, with a wheelbase of four feet and eleven inches, was powered by a water-cooled Chrysler six-cylinder 230-cid flathead gasoline engine of 6 2hp, with a three-speed “crash” gearbox that could reach a maximum speed of 15 mph. Production began in 1942, and by the end of the war Clark had delivered thousands of different cargo handling vehicles, including an order for more than 1,500 Clarktor 6s for the British Royal Air Force. These were built as a version designated “BH”, standing for ‘British Heavy’, and supplied to Ministry of War Transport for the RAF under the Lend Lease Act.
The Clarktor CT-6 morphed over the years, with the Model-E being the “The most popular of all Clarks now in service.,” according to Keystone Ground Support Inc., a company that sells parts for Ground Support Equipment. The Model-E, built from the late 1970s to mid 1980s, looks like this:
You might see some Clark Model-Es at airports these days, or you might see a CT-30/40/50. Here’s a service manual for a bunch of Clarktor models; the date hand-written on the cover is March, 1967:
You can see that these vehicles had L-head engines built by military engine-manufacturer Continental (who also built engines for the 1958 Willys FC-170 that I used to own) attached to manual transmissions that supplemented a traditional clutch disc with a fluid coupling.
You’ll also notice that the big plate of steel on the front of these Clarktors is called “Bumper Plates,” and they’re half an inch thick!
Clark offered a number of different models, with diesel or gas engines, with manual or automatic transmissions. One thing I found interesting when going through the user manuals were these comic-like operating instructions:
Also interesting is the answer to the question you were probably all wondering: “What exactly is it about these trucks that makes them good for towing?” The engines are definitely long-stroke, and therefore make good torque. But beyond that, it’s the gearing — and not in the transmission. Check this out:
The transmission’s first gear ratio is a fairly standard 3.7:1, but that rear axle ratio: Wow — 17.311 to 1!
A typical hard-core rock crawler will have maybe a 5.38:1 axle. To have three times that axle ratio is incredible. Combine that with a fluid coupling that reduces shock loads and presumably offers further torque multiplication, and you end up with a low-speed (up to about 15 mph) tugging beast!
The Clarktors were around from 1927 until the mid 1980s, and though some are still in service, they aren’t the only luggage-tugs you’ll see at an airport. In fact, at LAX the tugs I saw were from Harlan, a Kansas City-based company that started by renting out and fixing forklifts, and then decided to build its own version of the Clarkstor. From Harlan’s website:
In 1962 Mr. Kaplan founded Harlan Corporation to rent and rebuild lift trucks. While repairing these lift trucks, Jim analyzed the causes of component failure, and found that high failure parts were not available. So, he redesigned the parts, developed sources for new designs, and bought the parts to repair his customers’ lift trucks. He then went to the Lift Truck OEM and offered to sell the improved designs. At that time, the Lift Truck OEM was not interested, but later implemented these design improvements. This drive to reengineer components, to improve reliability and reduce costs, is at the heart of Harlan’s operations today.
Soon, Jim was selling parts all over the world. In the process, he developed lifelong friendships in over 70 countries, with both customers and suppliers. Harlan’s key supplier relationships are a strength built over a 35 year period. During this time, the business was growing rapidly, driven by development of improved forklift parts for a global market.
In 1968, a customer in Venezuela asked Mr. Kaplan to make towing tractors. So, Jim went out, bought a Model E Clark, and reengineered it. Harlan Corp. had all of the required parts in surplus inventory. The first twenty-five (25) tractors took two months to design and produce, since they only required the development and production of the frame to prepare for final assembly.
Here’s a closer look at a Harlan luggage-tractor:
There is a roofed-version, in case you’re curious:
Another brand that offers luggage-tractors is TUG, which is actually quite popular today. These vehicles even more like that Clarkstor first shown way back in 1927:
Here’s a bit of history on TUG via aviationpros.com:
1973 – TUG Manufacturing Corp. is founded. Core business begins with production of baggage tractors, primarily the Model MA, which is still produced today. TELL story of tug at Museum. Tug eventually expands its product line and introduces its Model 660 belt loader. In 1998, Stewart & Stevenson buys the company and becomes known as S&S TUG. The combination of TUG and S&S’ airport division provides the GSE industry its broadest product line. S&S TUG then merges with Davco Industries, a specialist in regional airline equipment broadening the line further.
After an ownership change in 2005, TUG’s name is changed to TUG Technologies Corp.
In September 2009, TUG donated a restored Tug Serial No. 001 to the Musuem of Commercial Aviation, Forest Park, GA. The company’s first tractor was delivered to Epps Airport Service at Peachtree-DeKalb Airport on Oct. 8, 1973. Realizing the importance of keeping this part of its history, TUG bought the tractor from Key On Ground Services in Clearwater, FL.
It’s actually quite incredible that the formula remained essentially the same for an entire century!
Now that I’ve gone down this deep rabbit-hole researching this article, I really want one. Lucky for me, I found this for sale on eBay!:
It even comes with luggage trailers!
I retired from the Postal Service in 2005, they still had some of these with manual transmissions moving mail at MSP airport. Was hilarious when they put someone who’d never driven a manual on one…
NMC-Wollard is another manufacturer that makes tugs in various sizes. We use 5 of them to push around incapacitated transit buses.
Tell me about these transit buses…
Oooh, what ya wanna know? I can hit your e-mail if you like. I’ve been a truck & coach mechanic for 18 years, and now technical instructor for 2 years. I’ve been at my transit agency for 8 years.
There is a Clark tug hidden under this kiddie train sheet metal somewhere I’d guess. It’s from the small town I grew up in Australia. I rode that thing many times doing 5-10 mph as excited as a wee kid can be. I’d guess someone got the Clark free or cheap from somewhere.
https://www.facebook.com/share/p/E9udR5dfBVFhQCSi/?mibextid=WC7FNe
The Tug MA still uses an old Ford style split rear with a bull gear reduction, a bit like a Winters Quickchange. The vast majority of these still run the old Ford 300, complete with its one barrel Holley and a C6 automatic.
I love that service manual with the dimensions in it. I love a good mechanical schematic or diagram, and I especially love pre-CAD ones. Someone *drew* those. There’s something very romantic about that to me.
I once (okay, maybe twice) watched a video from the 40s or 50s about how rivets function. It was fascinating, informative, and even a bit relaxing.
Old technical videos/documentaries are just awesome in general. I went down a rabbit hole a while back of a bunch of videos GM made back in like the 1930s, which talk about the engineering that goes into their cars, how everything works, and why it’s designed that way.
Those videos do a fantastic job of explaining all sorts of engineering principles in a clear, understandable, and interesting way. And all with that fantastic old documentary narrator voice that was everywhere back then.
Honestly I think a lot of teachers today could benefit from making their lessons more like those old documentaries.
Find yourself on the Periscope youtube channel some day. 40 minutes of a 1960s Caterpillar grader instruction video? They got you.
My Dad worked at a Clark forklift dealer when I was a kid. I always look to see if forklifts are Clark and now I will look for the little Clarktors.
StillNotATony says get 2 and race them! But I don’t understand how nobody has shared the advert by Cadbury’s chocolate in the UK, scarily 15 years ago…. https://youtu.be/cUnSe7XhtR4?si=B-7abrroA1OUQxEX
I’ve wondered about the steel plate on the front of these things. Does weighing down the front also prevent the rig from wheelie-ing while pulling heavy stuff?
Says right on the manual, for pushing. And I’d say pushing ANYTHING!
If, on your journey, should you encounter God, God will be pushed.
I’ll punch the asshole in the face if I ever encounter him.
Oh the implications of warning No. 19!
“Tug” means a lot of things
There’s a whole Tobias Fünke-like subplot here where David goes out in LA looking to purchase a tug.
“Hi, I’m here for the rub-n-tug?”
“Through the curtain.”
“But where will they wash my tractor?”
“I said through the curtain, we got a line here.”
*Hot Cops ensue*
I really like this kind of car-adjacent but totally interesting content. In my opinion, to make a proper automotive utopia, we need to include all things that are auto motive.
I am VERY interested in what it’s like to drive one of these with the fluid coupling but also clutch and manual transmission. I have long pondered the possibilities(and potential issues) of a manual transmission with a torque converter, because that would eliminate what is IMO the only real disadvantage of manual transmissions: slipping the clutch.
The first Clark to Moab!
it’s got DT written all over it.