Something I’ve never thought about but my Mrs said today why don’t lorries hum any more when 1 is being overtaken by another ? Well I don’t know anyway 
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Punchy Dan:
Something I’ve never thought about but my Mrs said today why don’t lorries hum any more when 1 is being overtaken by another ? Well I don’t know anyway
You can’t beat a “Hummin ■■■■■■■■ Dan. Wonderful on full song !! 
Regards Kev.
Your right there Kev ,but I was thinking may be higher geared / speed limited and smoother engines or turbo engine perhaps ?
I wonder if she was referring to that throbbing set up by two sets of engine pulses beating at different speeds. The reason we no longer hear this is probably a combination of very high engine sound insulation and the fact that cars / truck cabs are so well insulated. Robert
Less gearbox noise?
not as good as the whine of a Roadtrain diff.
Humms (note the spelling, Dan) were outlawed by the EEU in 2012 due to the emotional effect they were having on women. It took quite some time to round the little blighters up but it is believed that most of them have been humanely dispensed with.
There are, however, a few small enclaves of Humms still at large around the U.K. Examples can be found in the worm drive diff’s of some old Fodens as well as those hiding in the transmissions of O-model Bedfords.
There is an unsubstantiated report that a few Humms have morphed into Whisstles and have burrowed into Volvo turbochargers.
Members of the public and in particular. lorry drivers are urged to keep a keen ear out for these little terrors in case they start to breed again. Sightings- or “hearings”- should be reported to VOSA without delay.
ERF-NGC-European:
I wonder if she was referring to that throbbing set up by two sets of engine pulses beating at different speeds. The reason we no longer hear this is probably a combination of very high engine sound insulation
I think the word describing that sound is thrum not hum ?.
youtube.com/watch?v=ss54yiTjwmo
youtube.com/watch?v=49CpQJ4G8wA 1.00-2.18 although sounds more like a recording of take off run and climb to height and cruise than engine warm up at that point. 
IT is very possible that the Mythical Humm disappeared around the same time as the Guy Big J 8LXB!!! 
Only a Thought, maybe the right Nonarable Gentleman From Kendal could elaborate / confirm?
E.W.
Honourable Even!!! 
E.W.
Carryfast:
ERF-NGC-European:
I wonder if she was referring to that throbbing set up by two sets of engine pulses beating at different speeds. The reason we no longer hear this is probably a combination of very high engine sound insulationI think the word describing that sound is thrum not hum ?.
youtube.com/watch?v=ss54yiTjwmo
youtube.com/watch?v=49CpQJ4G8wA 1.00-2.18 although sounds more like a recording of take off run and climb to height and cruise than engine warm up at that point.
+1
Robert
The second video clip reminds me that my parents both told me that during WW2 it was possible to tell the difference between one of ‘our’ 'planes and one of ‘theirs’ by sound alone. The German 'planes always droned or hummed with a regular beat whereas the RAF bombers did not. I have since read that after take off it was the job of an RAF flight engineer to synchonise the engines (rpm) so that the droning noise disappeared. It seems also that sometimes when an RAF bomber was off course and found itself over a heavily defended area alone, that the crew deliberately desynchronised the engines in the hope of bluffing their way through.
Humming… perhaps it’s engine harmonics that your thinking of… Many years ago in the UK and across Europe if you were in certain kind of truck and were overtaking another truck, then as you pulled even with the middle of the trailer and progressed farther along side you often became aware of a kind of rhythmic throbbing sound which would get faster the farther along the other truck you got. Usually by the time your cabs got even the harmonics would quickly fade and stop. Box vans and fridges used to enhance the sound… probably with the sound echo bouncing of the harder surfaces… I often wondered if you were standing at the side of the road when it happened would you hear it… or was it only audible in the cab…
A Barbers Quartet … 4 blokes ( or even woman ) singing in harmony, when done right, can, to the ear, sound like they have at times 5 singers… again harmonics… or the oscillation of sound waves creating another harmony…
In the trucks of today it’s very hard to even witness this effect as they tend to run a lot quieter, and have a lot of sound suppression fitted around the engine and running gear in general, which does its job quite well of cutting out as much sound frequency as possible…
I used to love getting past other trucks in my old Gardner powered Sed Atki as more often than not I could experience the “hollow effects” of engine harmonics…
The last time I experienced engine harmonics was only a few weeks ago when I was out for a bit of bash in the old FLB Freightliner … Detroit powered, you can clearly see the engine in the chassis rails if you look under the cab… I just managed to out drag my mate in his restored Kenworth 123 ( like Firderici used to have ) with a 2 stroke in it… It sounded like a riot on wheels and it did take us about 2 minutes longer than my big banger to get up the hill, but I heard very clearly Humming as I was getting round him…brought back a few memories…
Jeff…
cav551:
The second video clip reminds me that my parents both told me that during WW2 it was possible to tell the difference between one of ‘our’ 'planes and one of ‘theirs’ by sound alone. The German 'planes always droned or hummed with a regular beat whereas the RAF bombers did not. I have since read that after take off it was the job of an RAF flight engineer to synchonise the engines (rpm) so that the droning noise disappeared. It seems also that sometimes when an RAF bomber was off course and found itself over a heavily defended area alone, that the crew deliberately desynchronised the engines in the hope of bluffing their way through.
I think all of us,with WW2 generation connections who lived through the Lufwaffe air attacks,were told the same.That’s why I posted that example.Absolute proof that their ears and their stories were accurate.
As for the Lanc at least compared to the German twins the motors seem to be more or less in synchronous harmony sounding like one V12 from takeoff.
ERF-NGC-European:
Carryfast:
ERF-NGC-European:
I wonder if she was referring to that throbbing set up by two sets of engine pulses beating at different speeds. The reason we no longer hear this is probably a combination of very high engine sound insulationI think the word describing that sound is thrum not hum ?.
youtube.com/watch?v=ss54yiTjwmo
youtube.com/watch?v=49CpQJ4G8wA 1.00-2.18 although sounds more like a recording of take off run and climb to height and cruise than engine warm up at that point.
+1
Robert
Thrumms are a very different creature altogether and are not subject to the same EU directive as Humms. In fact there is a movement afoot to have Thrumms classified as an endangered species as their habitat (the rear two pots of a Big J/240 Gardner) seems to be disappearing faster that the Arctic ice cap.
Retired Old ■■■■:
ERF-NGC-European:
Carryfast:
ERF-NGC-European:
I wonder if she was referring to that throbbing set up by two sets of engine pulses beating at different speeds. The reason we no longer hear this is probably a combination of very high engine sound insulationI think the word describing that sound is thrum not hum ?.
youtube.com/watch?v=ss54yiTjwmo
youtube.com/watch?v=49CpQJ4G8wA 1.00-2.18 although sounds more like a recording of take off run and climb to height and cruise than engine warm up at that point.
+1
Robert
Thrumms are a very different creature altogether and are not subject to the same EU directive as Humms. In fact there is a movement afoot to have Thrumms classified as an endangered species as their habitat (the rear two pots of a Big J/240 Gardner) seems to be disappearing faster that the Arctic ice cap.
Is it true that Humms and Thrumms are the grand-sons and grand-daughters of Gremlins - sort of aural versions of Cherubim and Seraphim, ROF, as you have some expertise in these matters? Robert
Aha! Robert, you are of an age to remember the dreaded Gremlins?
I have been pestered by gremlins all my life, mainly because they also reside in some of the automotive disasters that have come my way! They would creep in from somewhere- much like couch grass will in the horticultural world- when you’re least expecting them. They seem to be particularly attracted to the smell of burning oil which may explain why they were always to be found in just about all the 2-stroke engines of my acquaintance. They even put in a one-off appearance in the valve-operated 5-watt radio that I was attempting to listen to the commentary of the IOM TT on. The ■■■■ thing cut out just after the start of the programme and, despite several applications of a clenched fist, couldn’t be coaxed back into life until the broadcast was over. We had no tinterweb in those days so I had to wait until the motorcycle press told me that Bob McIntyre had made the first 100 mph lap.
To turn to your subject of cherubims & seraphims I would gladly have exchanged a right upper limb for a pair (or even three pairs!) of appendages which adorn these beings. Maybe, had I been so equipped, I would have managed the journey times expected by an ex-employer of my 150 Gardner-powered 8-wheeler Atki.
Retired Old ■■■■:
Aha! Robert, you are of an age to remember the dreaded Gremlins?
I have been pestered by gremlins all my life, mainly because they also reside in some of the automotive disasters that have come my way! They would creep in from somewhere- much like couch grass will in the horticultural world- when you’re least expecting them. They seem to be particularly attracted to the smell of burning oil which may explain why they were always to be found in just about all the 2-stroke engines of my acquaintance. They even put in a one-off appearance in the valve-operated 5-watt radio that I was attempting to listen to the commentary of the IOM TT on. The ■■■■ thing cut out just after the start of the programme and, despite several applications of a clenched fist, couldn’t be coaxed back into life until the broadcast was over. We had no tinterweb in those days so I had to wait until the motorcycle press told me that Bob McIntyre had made the first 100 mph lap.
To turn to your subject of cherubims & seraphims I would gladly have exchanged a right upper limb for a pair (or even three pairs!) of appendages which adorn these beings. Maybe, had I been so equipped, I would have managed the journey times expected by an ex-employer of my 150 Gardner-powered 8-wheeler Atki.
And we mortals are left with just the stubs, often known as shoulder blades. Gremlins were attracted to LandRovers too, much as ground-elder to an unsuspecting garden. Alas! Robert
ERF-NGC-European:
Retired Old ■■■■:
Aha! Robert, you are of an age to remember the dreaded Gremlins?
I have been pestered by gremlins all my life, mainly because they also reside in some of the automotive disasters that have come my way! They would creep in from somewhere- much like couch grass will in the horticultural world- when you’re least expecting them. They seem to be particularly attracted to the smell of burning oil which may explain why they were always to be found in just about all the 2-stroke engines of my acquaintance. They even put in a one-off appearance in the valve-operated 5-watt radio that I was attempting to listen to the commentary of the IOM TT on. The ■■■■ thing cut out just after the start of the programme and, despite several applications of a clenched fist, couldn’t be coaxed back into life until the broadcast was over. We had no tinterweb in those days so I had to wait until the motorcycle press told me that Bob McIntyre had made the first 100 mph lap.
To turn to your subject of cherubims & seraphims I would gladly have exchanged a right upper limb for a pair (or even three pairs!) of appendages which adorn these beings. Maybe, had I been so equipped, I would have managed the journey times expected by an ex-employer of my 150 Gardner-powered 8-wheeler Atki.And we mortals are left with just the stubs, often known as shoulder blades. Gremlins were attracted to LandRovers too, much as ground-elder to an unsuspecting garden. Alas! Robert
Excuse the interruption gentlemen, but aren’t Gremlins a factory-fit non optional extra in Landys? They aren’t listed in the spec sheet but are always there.
Similarly the Tin Worm is present in older cars, Fiats especially. It is a variety native to the northern climes, where the steel is mined, and becomes torpid in sunny weather. However it becomes active again in northern winters.
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Franglais:
[quote="ERF-NGC-Similarly the Tin Worm is present in older cars, Fiats especially. It is a variety native to the northern climes, where the steel is mined, and becomes torpid in sunny weather. However it becomes active again in northern winters.
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Slightly(!) off topic…
Back in the 70’s I had a couple of Fiat Ritmos that I bought new and, as I tend to do, kept them for years. After about 9 years (and about 300,000 Kms of really quite trouble-free use-really) the old tin worm was very active.
Once, at a social gathering, talk turned to collecting objets d’art. I did no such thing but added to the conversation that I collected antiques, Italian antiques. When pressed whether I specialised I had to admit that my collection was exclusively Fiat.