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After watching the video below I wondered the reason for towbarless tugs. Lifting the front wheel of a 575 ton aircraft seems like it requires an awful lot of expensive and complex hydraulics when the goal is just to move the aircraft around on the ramp. What benefit is there to doing this over just using a towbar?

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    $\begingroup$ Most of the weight on an aircraft sitting on the ground is supported by the rear wheels. So that video isn't nearly as impressive as it may seem. $\endgroup$ – ratchet freak Oct 27 '17 at 8:07
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    $\begingroup$ Also, when your ultimate goal is to lift that 575-ton aircraft several kilometers into the air, lifting its front wheel a few centimeters doesn't seem like such a big deal. ;-) $\endgroup$ – David Richerby Oct 27 '17 at 19:29
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    $\begingroup$ It takes a hell of a lot more power to lift it than it does just to move it. At the air show in town my company usually flies in an A300 for a tug-of-war. They attach a rope to the nose gear and 10 people are able to pull it across the ramp. I seriously doubt those same 10 people could lift the nose. $\endgroup$ – TomMcW Oct 27 '17 at 19:37
  • $\begingroup$ @TomMcW see youtube.com/watch?v=cHhZwvdRR5c - if the aircraft is mistrimmed, it takes power to keep its front wheel down. Nosewheel carries about 4-10% of the aircraft weight. Those 10 people can speed up the plane and then roll its nosewheel on a 5cm tall ramp - boom, they've just lifted the wheel as the tug did. $\endgroup$ – Agent_L Oct 29 '17 at 17:09
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    $\begingroup$ @TomMcW - it doesn't take power to lift something, it takes force. With appropriate mechanical advantage, a single person can provide enough force to lift the nose of an airplane. Just as the tug doesn't lift the airplane through direct mechanical connection to the engine (it uses a hydraulic pump (probably) to give it the mechanical advantage that it needs), a person could use a 100 ton bottle jack to get the same mechanical advantage (though there are lots of other ways it could be done. $\endgroup$ – Johnny Nov 7 '17 at 23:47
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Advantages of towbarless pushback.

  1. You don't have to store different tow-bars for different a/c types. This is especially good for ground handlers who handle different airlines with different aircraft types. Also handy for ad-hoc one-off flights.

  2. Removing need for tow-bars means one thing less to check daily, weekly, monthly, annually.

  3. Towing with a tow-bar requires a man in the cockpit to ride the brakes (brake-rider). This also means the aircraft may require power (either from APU or from the towing vehicle) to supply hydraulic pressure. An aircraft towed with a towbar is dependent on the aircraft brakes if a sudden stop is required as the towbar will not be able to take the weight of the aircraft on its own on decelerations.

  4. A normal tug (which uses towbar) needs to be very heavy to enable it to tow an aircraft. Without the weight, the tug will just spin its wheels. The tow--barless tug will have the weight of the aircraft on its wheels so it doesn't need to be as heavy. Just solidly built to support the engine and associated hydraulic stuff. This weight also makes the brakes more effective.

  5. A towbarless can tow the aircraft faster as control is way better. In some busy airports they only allow you to move the aircraft across busy taxiways or during peak hours if it is either taxied under its own power or towed by a towbarless tug. Towing using tow-bar is not allowed as it is very slow.

  6. The tow-bar has 'shear pins' which limit the force which can be applied through the nosewheel towbar points. This reduces the towing speed. They can and do break once in a while. While a spare is usually carried in somewhere on the 'bar it still stakes a few minutes to get in installed. Not fun in the middle of a pushback and may result in a blocked taxiway.

  7. A lot of injuries are caused by towbars. Either they jacknife when something fails or a lapse in procedure caused the nosewheel steering to be activated before the bar has been disconnected. The danger here is the nosewheel is self-centering in almost all aircraft and will swing the bar if the nosewheel is not centered. Scary to see and can take your legs out.

I'm sure there are more aspects but these are the major points. Hope this clarifies a bit.

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    $\begingroup$ AKA the real cost is the logistics, not the price. Very true, but often not intuitive. $\endgroup$ – fectin - free Monica Oct 28 '17 at 17:22
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    $\begingroup$ With a towbar, doesn't someone need to manually attach it and with that lift you can just drive it? Must be faster and nicer in bad weather. $\endgroup$ – PlasmaHH Oct 29 '17 at 20:24
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I didn't see this mentioned in Anilv's answer so it may only apply to light aircraft. In general aviation space, towbarless tugs can also allow for 180 degrees of rotation while keeping the nosewheel straight allowing for greater maneuverability than a towbar alone which is limited by the amount your nosewheel can turn. I have used one called the AircraftCaddy that does this. Doesn't add much for a plane with a free-castering nosewheel but definitely aids maneuverability in one with a steerable nosewheel.

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    $\begingroup$ That's pretty nifty. Like a pallet jack for your airplane. $\endgroup$ – TomMcW Oct 27 '17 at 17:49
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    $\begingroup$ I enjoy the contrast between the linked "towbarless tug" and the one in OPs video. $\endgroup$ – JPhi1618 Oct 27 '17 at 18:51
  • $\begingroup$ MattD, Commercial airliners have limits as to how much the nosewheel can turn. You often see red stripes or a hatched area on the nose wheel door to indicate the nosewheel should not be turned past that point. While it is possible to disconnect the drag strut (the traingular linkage which connects the top and bottom portions of the nose sear), it is not done as a practise and is usually done to retrieventhe aircraft fro an unnatural parking where a normal tug/towbarless would not get in. $\endgroup$ – Anilv Oct 30 '17 at 1:14
  • $\begingroup$ oops.. I see that you meant the towbarless can run 180 degrees while nosewheel is straight. I misunderstood, sorry. $\endgroup$ – Anilv Oct 30 '17 at 1:17
  • $\begingroup$ You can see it a little bit in the video linked in my post, couldn't find a good video showing a full 180 degree turn with the nosewheel straight. $\endgroup$ – MattD Oct 31 '17 at 2:36

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