vaus77w From Australia, joined Aug 2011, 54 posts, RR: 0 Posted (3 months 4 weeks 11 hours ago) and read 4846 times:
I've always been curious about airport tug vehicles.
Do all tugs have the same capability- ie, can they push back anything from a Dash 8 to an A380 or do you need different sized tugs for different aircraft sizes?
Also, are the tow bars from the tug to the nose gear universal to all aircraft types or do you need different attachments for each aircraft family (e.g 737, A320, 777 etc)?
Sorry if this is a stupid question, I did a search and could not find any posts on this topic.
BMI727 From United States of America, joined Feb 2009, 11547 posts, RR: 27 Reply 1, posted (3 months 4 weeks 11 hours ago) and read 4848 times:
Quoting vaus77w (Thread starter): Do all tugs have the same capability- ie, can they push back anything from a Dash 8 to an A380 or do you need different sized tugs for different aircraft sizes?
Definitely different ones for different planes. Some of the ones used for RJs seem to be the same as the ones used to haul bag carts around.
Quoting vaus77w (Thread starter): Also, are the tow bars from the tug to the nose gear universal to all aircraft types or do you need different attachments for each aircraft family (e.g 737, A320, 777 etc)?
I'm not sure if it's different attachments, but I do recall a story of a Delta 767 that diverted and was then stranded until they could find a towbar strong enough to be used on a plane that large. I want to say it was in LIT, but I may not remember right.
Of course the entire problem can be sidestepped with a towbarless tug.
Why do Aerospace Engineering students have to turn things in on time?
tdscanuck From Canada, joined Jan 2006, 11032 posts, RR: 72 Reply 2, posted (3 months 4 weeks 11 hours ago) and read 4779 times:
Quoting vaus77w (Thread starter): Do all tugs have the same capability- ie, can they push back anything from a Dash 8 to an A380 or do you need different sized tugs for different aircraft sizes?
It's a one-way street...tugs can handle anything below their rating but nothing above. So a really big tug, assuming you have a tow-bar to fit, can push anything from an RJ to an A380 but a tug that's just big enough for an RJ can't push an A380.
The issue is traction force...small tugs don't weight much and can't generate enough force to effectively move (and stop) big airplanes. They just spin their tires.
Quoting BMI727 (Reply 1): I'm not sure if it's different attachments, but I do recall a story of a Delta 767 that diverted and was then stranded until they could find a towbar strong enough to be used on a plane that large.
Across all OEM's it's usually one attachment but I'm not sure about across OEM's. There are mechanical fuse links in towbars (the fuses are there to protect the landing gear from overload)...a towbar from a smaller aircraft may break under the towing loads for a larger aircraft. A towbar for a larger aircraft will allow an improperly driven tug to overload the landing gear of a smaller aircraft. It's best to use the one matched to the aircraft but, if you can't do that, the next best thing is use a stronger towbar and be very very careful. Using a small towbar on a large aircraft is asking for a busted towbar.
Quoting BMI727 (Reply 1): Of course the entire problem can be sidestepped with a towbarless tug.
That sidesteps the tug problem but not necessarily the aircraft. Because towbarless tugs don't have mechanical fusing, it's a lot easier to overload the nosegear.
vaus77w From Australia, joined Aug 2011, 54 posts, RR: 0 Reply 4, posted (3 months 4 weeks 8 hours ago) and read 4571 times:
Thanks for the info guys!
Quoting tribird1011 (Reply 3): Across all OEM's it's usually one attachment but I'm not sure about across OEM's. There are mechanical fuse links in towbars (the fuses are there to protect the landing gear from overload)...a towbar from a smaller aircraft may break under the towing loads for a larger aircraft. A towbar for a larger aircraft will allow an improperly driven tug to overload the landing gear of a smaller aircraft. It's best to use the one matched to the aircraft but, if you can't do that, the next best thing is use a stronger towbar and be very very careful. Using a small towbar on a large aircraft is asking for a busted towbar.
Quoting BMI727 (Reply 1):
Of course the entire problem can be sidestepped with a towbarless tug.
That sidesteps the tug problem but not necessarily the aircraft. Because towbarless tugs don't have mechanical fusing, it's a lot easier to overload the nosegear.
Tom.
How exactly do you overload the nosegear? I'm guessing if you jerk it by stopping/starting too quickly or turning too sharply?
wn676 From Bosnia and Herzegovina, joined Jun 2005, 598 posts, RR: 4 Reply 6, posted (3 months 4 weeks 8 hours ago) and read 4544 times:
Quoting tribird1011 (Reply 3): At YYZ, I have handled the same airplane (A320) for three different airlines, and I needed 3 different towbars
I didn't even realize the A320 family had different crossbar sizes until we handled a VX diversion about a month ago. We had to borrow a towbar from AC because none of ours were big enough to latch onto it, even though we can push our own 320s with them.
Tiny, unreadable text leaves ample room for interpretation
tdscanuck From Canada, joined Jan 2006, 11032 posts, RR: 72 Reply 7, posted (3 months 4 weeks ago) and read 4381 times:
Quoting vaus77w (Reply 4): How exactly do you overload the nosegear? I'm guessing if you jerk it by stopping/starting too quickly or turning too sharply?
Exactly. With a conventional tug, all the acceleration forces go through the towbar. As a result, as long as the towbar is the weakest link in the chain (which it's designed to be) it will break before you apply too much force to the gear (by starting or stopping too fast or trying to drag too tight a corner). A towbarless tug acts directly on the nosegear and, without sophisticated control systems, can apply as much force to the gear as the tug is capable of generating regardless of what the nosegear can actually withstand.
KELPkid From United States of America, joined Nov 2005, 5610 posts, RR: 4 Reply 8, posted (3 months 3 weeks 6 days 21 hours ago) and read 4316 times:
Quoting vaus77w (Reply 4): How exactly do you overload the nosegear? I'm guessing if you jerk it by stopping/starting too quickly or turning too sharply?
Day #1 of work for line personnel handling aircraft: you are taught that most aircraft bigger than a GA piston twin (and even some GA piston twins!) have turn limits marked on the nosegear. You are taught how to constantly monitor those visually while an aircraft is under tow. So you should never overload it by turning too tight. You can overload the nosegear by jerking or being a leadfoot (i.e. accellerating or decelerating the tug too quickly). But, once you get into serious equipment at the big airport, as everyone says, there are fuse links in the gear...provided you are using the right tow bar
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fuelfool From United States of America, joined Feb 2011, 119 posts, RR: 0 Reply 9, posted (3 months 3 weeks 6 days 16 hours ago) and read 4202 times:
Quoting BMI727 (Reply 1): Of course the entire problem can be sidestepped with a towbarless tug.
A tow bar-less tug doesn't always solve the problem. There are different sizes of them. FX has larger ones for use on the 777. Another company I worked for had ones significantly smaller than the ones FX uses for the rest of the fleet. Ironically, the tow bar for the 777 is less beefy than the one for A300/310. The bar for the MD10/MD11 is same. The bar for the 757 is different than the 727.
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737tdi From United States of America, joined Sep 2007, 317 posts, RR: 0 Reply 10, posted (3 months 3 weeks 6 days 13 hours ago) and read 4151 times:
Very strange that the same type of aircraft for different operators would have different towbars??? Every B737 I have moved/towed has had the same tow link on the nose gear. I would guess that is at least 10? different operators.
Now DC8's and DC9's used a completely different type of hookup.
With the B737 broken shear bolts in the towbar are not uncommon. We do not use the hydraulic steering depressurization valve when towing so verification of "A" system hydraulics being off is imperative or you will snap the shear bolt. Some airlines use the steering depressurization valves and some don't.
Tristarsteve From Sweden, joined Nov 2005, 3489 posts, RR: 35 Reply 11, posted (3 months 3 weeks 5 days 23 hours ago) and read 4005 times:
Quoting BMI727 (Reply 1): Of course the entire problem can be sidestepped with a towbarless tug.
Until the ramp is icy, then a TBL starts being a nuisance.
Real tugs are heavy. They are 25 to 40 tons of weight. This pushes the wheels onto the ground. The reason they are so heavy is to STOP the aircraft, otherwise you will put the brakes on. and the aircraft will keep going!
It is easy to tow an aircraft with a too small tug, but impossible to stop it.
But a TBL weighs a few tons only, and on ice the wheels just spin around.
Many times I have seen the A330 being pushed back in the snow at ARN. All goes well across the apron, which is heated, but leave the apron and the tug just stops. We try shovelling sand under the tyres, or sometimes a deicing truck can melt the ice, but in the end a trip to the hangar to collect the B744 tug and towbar is required.
A TBL 190 willl handle all aircraft from an E170 up to a B777. The B744 needs a special tug as the nosewheels are so big.
Tristarsteve From Sweden, joined Nov 2005, 3489 posts, RR: 35 Reply 12, posted (3 months 3 weeks 5 days 22 hours ago) and read 3964 times:
Quoting tdscanuck (Reply 2): Across all OEM's it's usually one attachment but I'm not sure about across OEM's.
Actually the B767 towbar also fits the Tristar DC10 A300 A310 A330 A340 and B777.
But it is not stressed for these heavier aircraft. I have used a B767 towbar to push out a B777, and we have it in writing that it is OK, but with engines off, and in a straight line, or you will break the shear pins.
Apart from this most towbars are different.
It has always amazed me that towbars, and aircraft wheels and brakes are all completely different. There are no standards at all.
Even across the same type. I needed a B767 Brake unit last year, and whizzed over to Tuifly to borrow one, but theirs was Dunlop, and we had Goodrich and we were AOG!
Now a towbar story.
BA operated the Concorde to hundreds of odd airports. It needed a special towbar (of course). So BA made an adaptor, which fitted on a B747 towbar at one end, and the Concorde noseleg at the other, and carried on all off route flights.
So the one and only time I was on the headset to push back a Concorde at ARN, after the pushback, I had to disconnect this adaptor and tie it onto a rope hanging from the R1 door, so the flight engineer could pull it back onboard!
Fabo From Slovakia, joined Aug 2005, 826 posts, RR: 1 Reply 14, posted (3 months 3 weeks 5 days 16 hours ago) and read 3848 times:
Quoting notaxonrotax (Reply 13): I recently heard that the AN-225 requires 2 heave tugs in-line to be moved.
How do they go around that when she happens to have an "odd" port call?
That makes sense, it has two nosegear after all.
Judging by its sheer size, however, I doubt that it is going to park nose-to-building somehwere anyway, even if it was not to be nose/loaded.
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rwessel From United States of America, joined Jan 2007, 1614 posts, RR: 2 Reply 15, posted (3 months 3 weeks 4 days 9 hours ago) and read 3564 times:
Quoting Fabo (Reply 14): Quoting notaxonrotax (Reply 13):
I recently heard that the AN-225 requires 2 heave tugs in-line to be moved.
How do they go around that when she happens to have an "odd" port call?
That makes sense, it has two nosegear after all.
The B-52, with a somewhat similar gear arrangement, uses a Y-shaped tow bar, I'd expect similar for the An-225. I think the prior comment was saying that they needed to hook two tugs end-to-end, not one to each nose gear, which would have space and control issues.
atct From United States of America, joined Mar 2001, 1902 posts, RR: 48 Reply 16, posted (3 months 3 weeks 2 days 19 hours ago) and read 3305 times:
At delta we had different tow bar attachments for Md-80's, 737's, 757/767's, and 777. The Md-80 tow bar was always Md-80's as at our station we had mostly Md-80's. The boeings had different head attachments but used the same tow bar from what I remember (big ole sob). The CRJ's had a little tiny tow bar. We had 2 pushbacks that we used. Our larger pushback was used for Md-80's and up with the smaller one Md-80's down. We didnt have any baggage tugs at our station that we used for RJ's. I know the CLE station did this though.
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sprout5199 From United States of America, joined Feb 2005, 1673 posts, RR: 2 Reply 18, posted (3 months 3 weeks 2 days 6 hours ago) and read 3182 times:
I have a question about the barless tugs. How do you get the nose wheels onto it? Push the tug under the wheels or pull the wheels onto it.?
notaxonrotax From Netherlands, joined Mar 2011, 359 posts, RR: 0 Reply 19, posted (3 months 3 weeks 2 days 1 hour ago) and read 3124 times:
Quoting rwessel (Reply 15): I think the prior comment was saying that they needed to hook two tugs end-to-end, not one to each nose gear, which would have space and control issues.
That is correct.
In-line……one in front of the other.
Do tow trucks have a forward connection for beasts like AN-225?
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Fabo From Slovakia, joined Aug 2005, 826 posts, RR: 1 Reply 20, posted (3 months 3 weeks 1 day 19 hours ago) and read 3027 times:
Quoting sprout5199 (Reply 18): I have a question about the barless tugs. How do you get the nose wheels onto it? Push the tug under the wheels or pull the wheels onto it.?
Put it "around" the wheel. Tugs have a fork-like shape with opening, and can sort of hold the wheel from front and back.
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DocLightning From United States of America, joined Nov 2005, 14050 posts, RR: 55 Reply 23, posted (3 months 2 weeks 6 days 14 hours ago) and read 2758 times:
Quoting Fly2HMO (Reply 22): Some other cool things you can do with the ridiculous amounts of torque tugs have
I understand that at low speeds (stop) most internal combustion engines have poor torque.
Has anyone made an electric or hybrid-electric tug? It would seem to me to be the perfect application of an electric drive.
Fly2HMO From , joined Dec 1969, posts, RR: Reply 24, posted (3 months 2 weeks 6 days 12 hours ago) and read 2744 times:
Quoting DocLightning (Reply 23): I understand that at low speeds (stop) most internal combustion engines have poor torque.
You're overlooking the fact that tugs have transmissions with really high gear ratios. In other words the engine may be screaming at 5000 rpm yet they'll barely go over 30mph, however they trade HP and speed for torque. Hence why you can pull those stunts on them. Not to mention engines can be engineered to produce maximum torque at either very low RPMs or very high RPMs, or most anywhere in between*
*a gross oversimplification, mind you.
Quoting DocLightning (Reply 23):
Has anyone made an electric or hybrid-electric tug? It would seem to me to be the perfect application of an electric drive.
There's tons out there. No, don't expect to see any Prius look-alikes out there. But you'll probably find Electro-hydraulic, series diesel electrics, and possibly diesel-hydraulic I believe.
25 darksnowynight: I don't know who makes them, but MQ uses the hell out of those things here at the DFW station. They don't even have seats; you just stand on the back
26 737tdi: Almost all of our pushbacks and bag tugs are electric here in DAL. I was skeptical when we first started using them but they actually work quite well
27 Larshjort: Are they Lektro's?I have worked at a company were we had the shortest model which was quite a challenge sometimes. But on other than long nosed aircr
28 sprout5199: Thanks, quite interesting. Dan in Jupiter
29 bjorn14: How do you calculate tug performance as related to the a/c by MTOW or other weights?
30 tdscanuck: On the tug side, you need drawbar pull and traction wheel load. You combine that with the surface, the number of running engines (at idle), and the s
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