Yeah, towed...
Hey Aruba-
Yes, they really, really, really mean 'towed'. I have a '68ish Clark IT60... TALL mast (it stands 13' with forks down). My forks are shaft mount, and there's retaining fixtures on the sides of the carriage where the forks can be flipped up over the fenders and CLAMPED in place, so that they're not sticking out to poke any cars that'd rear-end it.
There's many OTHER 'features' that make MINE towable...
Let's start with the suspension... drive axle is solid, and rigid to the frame, with Super Single-sized tires... not duals. The steer axle is SPRUNG... and it has caster and camber like an automotive/highway truck application... so when you're rolling 'backwards'(from the forklift op perspective), it will trail properly and not whip to one side or the other.
Hydraulic steering... it's 'non-feedback' type OPEN CENTER operation... so when it's sitting still, you can walk up to it, and push the steer axle side-to-side without much effort. This allows the wheels to steer when a typical hydraulic steering valve system would PREVENT motion. Once the engine pump is running though, the steering valve will keep the wheels pointed however the operator desires (or, that's the design intention, anyway).
Brakes... MY IT-60's 'towing kit' supposedly included a second master cylinder on the tow bar that served as 'surge brakes' for towing the machine. The way the brakes on the machine work, however, the leading-and-trailing pads are much more respectable travelling backwards (with respect to forklift operations) than forwards. They're really really grabby when driving as a forklift.
Oh... the driveline... Yeah, my IT-60 is SWEET... Slant-six swings a torque converter that drives a forward-neutral-reverse gearbox, which then feeds a four-speed truck gearbox, then the drive axle pinion. In FIRST gear, it goes something like 16mph. What it needs 2nd, 3rd, and 4th for, I don't know, but it's probably capable of 55mph or better in 3rd... and GOD HELP US if anyone ever were to try to drive it in anything other than first... because it uses a torque-converter, you can mash it up to speed, then step on the converter disengage pedal and coast down the highway (backwards, because it's too squirrly going forwards!)...
The hydraulics are all closed center... and the hydraulic pump is a variable ratio 'vane' type pump. This is really nice, because not only doesn't it need a pressure relief valve, the vanes retract when there's no pump flow. Really nice, too, when the engine is cold, because it doesn't have to try to pull a hydraulic pump in it's cranking load. Did I mention that when the hydraulic pressure is down, the steering system drops out, and allows the wheel steering to drop back? Yeah... so when you're blasting down the road at 25mph BACKWARDS, and you take your foot off the gas, dump the torque converter, and you'll clost and save fuel.. your steering goes away...
To inch up on a load, you let up on the torque converter 'dump' (inching) pedal... then give the engine some gas... the truck will pull forward... pull back on the carrige lift sticker, and it'll just kinda sit there. Hold the inching pedal and rev up the engine, so the hydraulic pump will flow... take your foot off the brake, and before it rolls too far back, engage the torque converter. It's gonna jump.. bark the tires, and stab a hole in your load... let up on the gas and the mast won't lift or tilt, and you'll have no steering... so you're damned.
So to make a long story much, much shorter...
My IT-60... is a technological PIG.
And there's a whole LOT of things that Clark SHOULD have done some other way. Fortunately, they've learned a little since then.
I'm amidst converting all these screwed up concepts to something that will work more sensibly, under very, very slow, sensible progress with a constant engine speed.