I had never considered the question before, but thought I'd share an answer I discovered in the explainlikeImfive subreddit:
Back in the late Cretaceous when I was learning to drive, most cars and trucks did not have power steering. Larger/heavier vehicles had larger steering wheels because you actually had to muscle the front rolling wheels around to turn the vehicle, and the additional leverage from a larger steering wheel was important. (Incidentally, you could tell if one of your tires was low because it literally got harder to steer. Local truckers and other frequent drivers tended to build up their arm muscles from navigating corners.) My dad's little MG sports car had a 13" steering wheel; my VW van had a 16" steering wheel; pickup trucks' were more typically 17"; and buses were more typically 18-20".Nowadays, practically every vehicle has power steering assist, but (CyberTruck aside) they're basically all designed so that if the power steering fails, you can still steer the car -- it's just harder to do so. So the big bus steering wheels are still around, as a safety measure.
Additional information at National Bus Sales:
A bus driver has to maneuver through lanes the same size as small cars but with a lot less clearance. With a smaller steering wheel, any adjustments could be too abrupt for safety. With a larger steering wheel, you can make a correction without changing the turning radius of the bus too dramatically. Smaller adjustments won’t cause any instability.
And this response to why the wheel is more horizontal:
This feature has changed over the years and varies in vehicles, but initially, the large steering wheels on buses sat almost horizontally. The driver sits directly above the tires, so for the steering column to correct the tires, the steering wheel needs to be positioned at a different angle. More recent bus models have options for the driver to adjust the position of the wheel.
Thank you, my knowledge is now increased.
ReplyDeleteBut it begs the question ... in my little Italian hatchback, which has viper quick steering, braking and acceleration, and they being all actuated by something called drive by wire ... should said wires fail, break, short out, get chewed by rampant possums, or cut by multi-tasking snippy demons roiling in laughter from reading the Divine Comedy ... will the needed brakes and steering still save my soul ?
I now have a need to find out.
Yes, your soul (and your hatchback) is safe. Modern drive-by-wire systems use heavy multi-layered redundancies and mandatory mechanical backups to ensure you always retain control of the vehicle.
DeleteFor the Brakes (Brake-by-wire): Even if a short, a possum, or a demon cuts the wires, the system has a failsafe push-through mechanism. A direct physical connection activates, forcing hydraulic fluid through the master cylinder to stop the car.
For the Steering (Steer-by-wire): If the electronic actuators fail, an active clutch physically reconnects your steering wheel directly to the front wheels. You might lose power steering assistance—making it heavy to turn—but the mechanical link remains intact.
For Acceleration: Should the throttle signal short out, the system's failsafe immediately forces the engine into an idle state, allowing you to brake and pull over safely.
I had several vehicles over the years without power steering, and in each of them I used an accessory you could buy from the auto parts store that clamped onto the wheel with a screw-down bracket and gave you a little spinny red wooden doorknob to quickly crank the wheel from lock to lock with one hand. The common term was /suicide knob/, maybe because somebody got their wizard sleeve tangled in it. I never had a problem.
ReplyDeleteSeveral of my extended family members may remember that our cousin Bruce had a suicide knob on the steering wheel of his car back in the 1950s, back when Naples was a small town in Florida.
DeleteSuicide knobs were for wimps. Manly men muscled their way through turns of the wheel.
DeleteSimilar reason for having a long tiller handle on a sailboat (or a big wheel) - you can make small adjustments.
ReplyDelete