Rob knows the way to his woman's heart is via her Unimog!
For my birthday last week (combined with Christmas), he bought me a 63cm Fiamm air horn with snow guard...
Here's a link to the sound:
Just imagine THAT a hundred times louder, resounding across the gardens... hahahaha!
Rob coupled it up briefly to the tyre inflation connection on Hans to see what it sounded like - it sounded like the QEII was coming in to dock!
I can't express how happy this present makes me!
Questions for you guys:
this horn has a range of 85-170psi, and I would love to give it the full 170psi, but probably not advisable! Was wondering where would be the best place to take a feed off the Unimog air system? Ours is an 18 bar system. Was thinking of possibly taking it off the auxiliary circuit where the exhaust brake is plumbed in, or looking at the handbook, the diagram suggests that the tyre inflation connection is 9.5 bar, which would do nicely.
We'll probably put a couple of Ts in for future fitting of air seats etc... next year's birthday prezzy maybe!
you should have two air tanks. One is intended to be a reserve brake supply. Don't tap into that one or you will deplete your brake pressure. The best would be to tap into the tank that you'd fill your tires from, run it through a regulator to drop that 18 bar down to 170psi and run that into a devoted 2gal or so air tank for things like the horn or seats.
these guys have kits, pumps and valves. might a place to get ideas. An old air compressor pancake tank and one of their valves would probably do it. I'm playing with the idea of a locomotive horn that I have laying around, but it might be just a bit too much...
The four-way protection valve is a component of the multi-circuit compressed air brake system for motor vehicles. It is part of the pressurizing plant and has the task to secure the individual compressed air circuits against each other. It is to be prevented that, in the case of pressure loss in one brake circuit, this also severely adversely affects another brake circuit. In principle, there are four overflow valves and non-return valves, which separate the individual circuits from one another. The circles are usually divided as follows:
Circuit 1: Service brake circuit 1
Circuit 2: Service brake circuit 2
Circuit 3: Spring accumulator parking brake and, if necessary, trailer supply
Circuit 4: secondary consumer (air suspension, door control, horn)
Since the compressed air brake system is a pure external brake system, a leak without protection of the other brake circuits would lead to the loss of the complete braking effect.
so, if the horn is conected to circuit 4 there will be no probs.
The "typical" installation for vehicles with on board air is to plumb a regulator valve and a surge tank after the air source and before the horn. The size of the tank dictates how long you can give'em the chrome finger and the regulated pressure controls volume and pitch. This way the worst case is you deplete the surge tank and not affect brakes & shifting etc. For vehicles without on board air, they make small pancake or log compressors which are activated with the horn which, provided your compressor and horn are match well, will provide air as needed.
Find your 4-way, find circuit 4, plumb a surge tank and you'll be letting everyone know who's going first through the round-about!
Tee the air supply on the back of the locker switch. That puts you on the correct tank at at a reasonable pressure (7.9 bar, Maybe? Anyway, less than 18bar tank pressure and on the correct tank.)
Thanks for the suggestion re the locker switch, Tmodler! Sounds like a sensible location. We'll have a look at that just as soon as we get the truck back from the workshop - it's off at the moment being fitted with a Webasto hydronic heater, new battery box and leisure batteries etc etc... lots of auto electrics. We'll be doing various bits of the work ourselves but our awesome auto electrician friend Mark, of Tyne Valley Auto Electrics in Prudhoe, has Hans in his shop right now doing the major electricals.
Hoping to get him back tomorrow, or at least by Friday, but we'll see... :grin
BTW, have seen various threads on plumbing hydronic heaters into the engine - is the best way to T into the heater matrix in the dash, or is it better to go for somewhere on the bottom radiator hose, or what? Suggestions welcome!
Our heater comes with both timer and thermostat, and a key fob remote - it's a secondhand heater off eBay, but sold by an ex Webasto engineer who has made a very tidy job of reconditioning a heater that's only a few years old. His wiring looms are works of art! :wink
Does the heater exhaust silencer make a big difference to the amount of sound? We had an Eberspacher D2 air heater without a silencer on our previous van, and it didn't make that much noise to our ears.
In my experience with our Eberspacher D5, the muffler does tame the exhaust noises quite a bit and a worthy addition.
Our current setup makes a "T" at the heater core line and returns to the bottom of the radiator just before the water pump. Seems to work out OK if bled properly. One downside is that if you want the hydronic loop to flow, you have to have the heater control set to hot. When set to cold it will restrict the flow of the entire hydronic circuit. When the circuit is set for heating the engine, it is common to have the heater control set to hot anyways so it isn't that big of a deal.
Update: we're in the process of getting some fittings for both the air horn and the hydronic heater. Why is it so hard to get hold of Ts and heater hose in the UK now? A while back you could pick it up anywhere, all the local motor factors carried it as a matter of course. Now... it's fine if you want a heater hose kit for a particular vehicle, but if you just want a length of heater hose, it's a special order. Bonkers! Looking like it might be an eBay moment... or an annoying trip into the nearest big city. :|
Plus point: got to go there for an interview anyway next week so we'll go via a couple of truck breakers in the city to try to pick up a smallish air tank for the horn. :devil
I splurged and have these in brass (McMaster has them) on my truck and they have been doing quite well for many years. Also there are conversion ones for metric to imperial depending upon what's more available for hose / tubing.
These should be common regardless of where you are. Have you checked out any lorry supply houses?
Well, A tank, anyway - we found ourselves a friendly truck breaker not too far away, and headed down there yesterday to see if he had any air tanks. Got a nice wee tank that will sit on the passenger side step without getting in the way of anything or anyone. It's about half as big again as the truck's existing air tanks, and after a bit of fiddling and guesswork, we identified it as a DAF tank with M22 metric threads. Got a nice brass drain valve today, with a mystifying metre-long coil of wire attached to it... anybody got any idea what this is for? The drain valves we have on the existing tanks don't have this wire.
Pictures coming soon!
:grin
Is the drain a poppet kinda valve or a ball valve kinda valve. Typically poppet valves have a cable so you can run it to a more convenient spot on the truck to stand while you observe. Imagine the tanks somewhere deep and far under the bodywork and a cable and little drain line extended close to a step etc. Few vehicle are designed & engineered like unimog in terms of function over form.
I have experienced the same thing when playing around with the valve. It is intended to be pushed in, however if you push sideways you are forcing the plunger to become off axis from the sealing surface which creates a small gap.
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