I read somewhere that you had to be registered disabled to use them on a road vehicle, my own opinion is that they are dangerous, they encourage one handed driving and would make it difficult to get hold of the wheel in an emergency. Anyone know if they are illegal or not.
Can I just clarify something. When you say steering wheel knobs are you talking about the ones behind the wheel or the ones you attach to the wheel? 
Although the two usually go together.
Any time i get in a truck with one fitted i take it off as i find it impedes my driving.
Along with soft toys and name plates in window!! 
Could never for the life of me work out why anyone would put one of those things on a truck steering wheel!!
The only time I could think of when I might have needed to turn a steering wheel that quick would maybe when backing an “A” frame drawbar into a restricted access or something similar but managed perfectly well without one.
As already stated, they belong in the same box as the frilly tassles, flags, name plates, blue lights etc!! 
Each to their own of course
Is Steering wheel knob slang for Tipper driver?
mike68:
I read somewhere that you had to be registered disabled to use them on a road vehicle
AFAIK this is the rule in some US states but not here.
Coffeeholic:
Can I just clarify something. When you say steering wheel knobs are you talking about the ones behind the wheel or the ones you attach to the wheel?
Yes very funny! the ones fixed to the wheel not the ones behind it. 
andy187:
Any time i get in a truck with one fitted i take it off as i find it impedes my driving.Along with soft toys and name plates in window!!
Grown men with soft toys in the cab, surely no.
sigh. 
mike68:
I read somewhere that you had to be registered disabled to use them on a road vehicle, my own opinion is that they are dangerous, they encourage one handed driving and would make it difficult to get hold of the wheel in an emergency. Anyone know if they are illegal or not.
More PC bs but we were palming the wheel without bothering with those back in the 1970’s and 1980’s.Who needs a knob when trucks have had decent power steering for years.
Coffeeholic:
Can I just clarify something. When you say steering wheel knobs are you talking about the ones behind the wheel or the ones you attach to the wheel?
You took the words right out of my mouth
it would fail an MoT with one fitted, so, read into that what you will
A few years ago 1 of our drivers fitted 1 to his FL7 and when he took it for the next inspection they took it off and told him it was illegal
One of ours has one fitted ; I had to take it out one day, hate the bloody things so I borrowed a spanner off the fitters and took it off. Driver played hell when he came back, so I told my boss in future I wouldn’t drive that wagon if the knob was fitted.
Agree with others, there are normally two knobs in the cab!
They are brilliant for cobbling cats
Wannabee Fork Lift Drivers
I have seen some older motors with a shaped bit on the rim of the steeing wheel ,presumably for this appendage . I think that they belong on flts.
They’re a PITA, I’ve ripped all the buttons off of a few shirts when I’ve got hooked up on them getting out of the cab
When I had my own trucks I charged a driver for a new steering wheel when his motor got a knock back at MOT for 1st, having one on the wheel & 2nd when they told me that as the rubber around the rim was now split it was a fail 
I also noticed that the people that fit them go through front tyres quicker too 
Brilliant piece of kit, especially when manouevring. If i had my own motor again, definately would not be without.
Even had one on a mini-van in 1977!
When i used to drive for P & O Ferrymasters out of Fleetwood, some units had them, some didn’t.
If i had the same unit, that had a knob fitted, a few weekends running, then got one without, i really missed it.
If i had free choice of units, as sometimes happened, I would choose one with a knob even if it was known to be not as well kept inside as one without. Just makes life easier.
Most units at Fleetwood were full time driver allocated. Knobs stayed on for years, never any problems with MOT tests.
Just as with the (thicker than steel) alloy wheels fitted but studs not changed, so they did not protrude through the nut.
I’d suggest that drivers who decry them don’t do a great deal of reversing in a shift or manoeurving in tight spaces. That quite possibly the manoeuvring aid has not been fitted in the correct position and that they do not ensure the wheels are straight & therefore the aid out of the way before leaving the cab.
As for tassled curtains pulled 1/2 way accross the side window, i can only think that the driver must be so ugly he is scared to be seen, or that he is working/driving illegally, or that he is consistently doing some illegal activity whilst driving.
we had a driver fit one to the wheel, but to get it to fit he had to carve a bit out of the wheel which ended up costing hundreds to fix when the vehicle went back to iveco.
mike68:
I read somewhere that you had to be registered disabled to use them on a road vehicle
Bullox
my own opinion is that they are dangerous
How? examples?
they encourage one handed driving
Suggest the next day you are out on the road you make a point of looking accross when you overtake another LGV or one overtakes you & take note if the driver has both hands on the wheel. You may be suprised. Please report back the results of your survey. (That does not indicate i condone 1 handed driving in any vehicle).
If you set you’re cruise control at 52mph you will run at the same speed as some companies, but many others will pass you adding to your survey numbers.
and would make it difficult to get hold of the wheel in an emergency.
Why? How so? The knob only takes up maybe 2 or 3% of the wheel’s circumference. If you don’t like the knob, what’s wrong with the other 97/98% ?
Would you not already be hold of the wheel in a developing situation?
Anyone know if they are illegal or not.
Not as far as i know.