Stu_davros Posted February 15, 2022 Share Posted February 15, 2022 Perhaps someone on here can help me with my curiosity: Today whilst driving along the M3 I passed a truck (not unusual so far), as I passed I noticed the wheel hub of the second axle (first rear axle) was connected with a hose to a device on the mud guard for the wheels in question. It seemed to be a standard truck you see on UK roads but I've never seen this hose connected to the hub. Anyone know what it does? Ta, Stuart Link to comment Share on other sites More sharing options...
Little Timmy Posted February 15, 2022 Share Posted February 15, 2022 (edited) Air pressure monitor ... ? I never had much use for them though. I could always tell when a tire was flat... just by all the debries flying around . It could also be a hub temperature sensor. Edited February 15, 2022 by Little Timmy Link to comment Share on other sites More sharing options...
Circloy Posted February 15, 2022 Share Posted February 15, 2022 22 minutes ago, Little Timmy said: Air pressure monitor ... ? Never understood how you could monitor tyre pressure on a rotating wheel until I got my current vehicle & it turns out you don't. The electronics measure the rotational rate of each wheel and if one differs from the rest indicates an issue. I'm perplexed as to what it could be that needs to come from the mud guard to the wheel hub, sensors would normally come direct from the chassis to the hub via the rear of the hub an as such hiden behind the wheels Link to comment Share on other sites More sharing options...
dcrfan Posted February 16, 2022 Share Posted February 16, 2022 It wasn't a central inflation system? Link to comment Share on other sites More sharing options...
richellis Posted February 16, 2022 Share Posted February 16, 2022 It’s a tyre inflation system, I’d guess you saw a logging truck as they use it to lower the tyre pressure on soft ground to aid traction, then re-inflate when back on the road 1 Link to comment Share on other sites More sharing options...
Stu_davros Posted February 16, 2022 Author Share Posted February 16, 2022 47 minutes ago, richellis said: It’s a tyre inflation system, I’d guess you saw a logging truck as they use it to lower the tyre pressure on soft ground to aid traction, then re-inflate when back on the road I can't remember what it was pulling Rich, but that does make sense. How does the central hub connect to the tyre? And why only one of the two rear axles? Thanks for everyones replies. Link to comment Share on other sites More sharing options...
richellis Posted February 16, 2022 Share Posted February 16, 2022 It’s probably only a single drive axle either a tag with the drive axle then a tag(lift rear axle non driven) so they drop the pressure in the drive tyres, then lift the rear axle to transfer the weight onto the drive axle, or a mid-lift (non driven axle in front of the drive axle, and looks like the front steer wheels) will do the same with the drive axle at the rear Used mainly in forestry but the tractor can also work with any trailer. It is connects via a swivel type joint and is piped to the tyre valves between the wheels. If I see one on my travels I’ll get some pics. Link to comment Share on other sites More sharing options...
richellis Posted February 16, 2022 Share Posted February 16, 2022 14 hours ago, Circloy said: Never understood how you could monitor tyre pressure on a rotating wheel until I got my current vehicle & it turns out you don't. The electronics measure the rotational rate of each wheel and if one differs from the rest indicates an issue. On a car it’s normally via the ABS sensor, looking for a difference in revolutions, unless your car will tell you the tyre pressure, then it’s a wireless sensor inside the tyre normally attached to the valve. Link to comment Share on other sites More sharing options...
Stu_davros Posted February 16, 2022 Author Share Posted February 16, 2022 3 hours ago, richellis said: It’s probably only a single drive axle either a tag with the drive axle then a tag(lift rear axle non driven) so they drop the pressure in the drive tyres, then lift the rear axle to transfer the weight onto the drive axle, or a mid-lift (non driven axle in front of the drive axle, and looks like the front steer wheels) will do the same with the drive axle at the rear Used mainly in forestry but the tractor can also work with any trailer. It is connects via a swivel type joint and is piped to the tyre valves between the wheels. If I see one on my travels I’ll get some pics. That makes sense, the wheels it was attached to were definitely driven as they had the right type of wheels, probably a lift axle on the back. Thanks for everyones responses, I am suitably educated. Link to comment Share on other sites More sharing options...
Stu_davros Posted May 16, 2022 Author Share Posted May 16, 2022 Another question, today as I was leaving work I saw a truck which had me wondering. At first sight It looked like a standard semi truck you see on British roads (a Scania I think ) but instead of the 5th wheel on the back it had a flat bed with a small load on it. Why would you need such a large truck for such a small load? Is it for transporting very small but very heavy loads? Cheers, Stuart Link to comment Share on other sites More sharing options...
richellis Posted May 18, 2022 Share Posted May 18, 2022 Did it have a large crane behind the cab? If so then it would be used to store chains etc on. or, it can be used to store ballast on and tow a trailer (drawbar or dolly) This is an over weight trailer so uses the ballasted locomotive style 2 Link to comment Share on other sites More sharing options...
Stu_davros Posted May 19, 2022 Author Share Posted May 19, 2022 Hello Rich, It had no crane or connection for a trailer. It was a 4x2 truck with a small flat bed on the back of the chassis instead of the 5th wheel. Link to comment Share on other sites More sharing options...
richellis Posted May 21, 2022 Share Posted May 21, 2022 It wouldn’t be a big hitch for a drawbar, and the 5th wheel would have probably been under the body, they are normally removable so it can be used either way Link to comment Share on other sites More sharing options...
Six97s Posted May 21, 2022 Share Posted May 21, 2022 (edited) How old was the truck? I've seen some restored tractor units with either no fifth wheel* or a small load bed. * There seems to be an urban myth that the fifth wheel has to be disabled somehow if using the vehicle without an operator's license. Edited May 21, 2022 by Six97s Link to comment Share on other sites More sharing options...
Stu_davros Posted May 21, 2022 Author Share Posted May 21, 2022 7 hours ago, Six97s said: How old was the truck? I've seen some restored tractor units with either no fifth wheel* or a small load bed. It was a newish truck (5 years old max), certainly not a restored unit. I think Rich has hit the nail on the head, it was probably a temporary flat bed for transport and the truck was being relocated for use shunting trailers. It was where I work at Farnborough airport and it was coming on site, possibly preparing for the Airshow in June. Cheers Guys. Link to comment Share on other sites More sharing options...
richellis Posted May 22, 2022 Share Posted May 22, 2022 On 21/05/2022 at 12:17, Six97s said: How old was the truck? I've seen some restored tractor units with either no fifth wheel* or a small load bed. * There seems to be an urban myth that the fifth wheel has to be disabled somehow if using the vehicle without an operator's license. It’s nothing to do with that’s, they put the small box in to weigh the back down as a solo tractor unit bounces lots, especially older lorries with short wheelbases and steel sprung suspension. It make a massive difference with traction and comfort. 1 Link to comment Share on other sites More sharing options...
Six97s Posted May 22, 2022 Share Posted May 22, 2022 4 hours ago, richellis said: It’s nothing to do with that’s, they put the small box in to weigh the back down as a solo tractor unit bounces lots, especially older lorries with short wheelbases and steel sprung suspension. It make a massive difference with traction and comfort. That makes sense. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now