Four-wheel maneuverability

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Re: Four-wheel maneuverability

Postby ShaneG_old » Fri May 22, 2009 5:34 am

On usual cars, turning steering wheel turns both axles, right?

How are the two axles separately controlled on a Coleman tug?


Same as any tug, Coleman, Schopff, Fresia, clever hydraulics and a computer or two if it is not older than 10 years or so.

Matt

I have only seen outside pictures of Coleman tugs. What is the inside like, what kind of driver controls allow 4 wheel steering to be separately controlled?


In all the tugs I have driven, it is push button control. And not quite sure what you mean by separately controlled? The options are generally, forward wheel steering, rear wheel steering, four wheel steering and the ability to crab, i.e all wheels pointing in the same direction, so you can go forward/backwards diagonally.

Matt



A fellow here has a Monster Truck and it uses this same system. :)
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Re: Four-wheel maneuverability

Postby expat » Fri May 22, 2009 9:08 am

On usual cars, turning steering wheel turns both axles, right?

How are the two axles separately controlled on a Coleman tug?


Same as any tug, Coleman, Schopff, Fresia, clever hydraulics and a computer or two if it is not older than 10 years or so.

Matt

I have only seen outside pictures of Coleman tugs. What is the inside like, what kind of driver controls allow 4 wheel steering to be separately controlled?


In all the tugs I have driven, it is push button control. And not quite sure what you mean by separately controlled? The options are generally, forward wheel steering, rear wheel steering, four wheel steering and the ability to crab, i.e all wheels pointing in the same direction, so you can go forward/backwards diagonally.


I mean, a steering wheel is a continuous input control. You could turn your front wheels 60 degrees from centered, or 30 degrees, or 53 degrees - and angle.

But I understand then that there is no separate continuous input control? You cannot turn your front wheels 50 degrees to the right and rear wheels 23 degrees to the right - you only have 3 options by push button, namely 50 degrees to the right if crabbing, 50 degrees to the left if 4 wheel steering, or 0 degrees if front wheel steering.

Correct?



Generally that is correct. I have seen cargo loaders that can do what you are asking, that being front and rear independent steering. When unloading an Air Bus fuselage for example, the loader is so long it is easier to line up rather be than go back and forth all day looking for that half centimeter to the left, whoops, now a half to the right.

Matt
Last edited by expat on Fri May 22, 2009 9:09 am, edited 1 time in total.
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Re: Four-wheel maneuverability

Postby KJC » Fri May 22, 2009 1:31 pm

[quote]I wish I had a dollar for everytime I got caught "high-speed" crabbing around the bomb dump in a Coleman Tug! ;D

The Colemans were able to do a 180 within their own length. :D

A time or two a month there'd come a call over the radio from the head-shed tower,
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Re: Four-wheel maneuverability

Postby expat » Fri May 22, 2009 1:53 pm

[quote][quote]I wish I had a dollar for everytime I got caught "high-speed" crabbing around the bomb dump in a Coleman Tug! ;D

The Colemans were able to do a 180 within their own length. :D

A time or two a month there'd come a call over the radio from the head-shed tower,
"A bit of a pickle" - British translation: A catastrophically bad situation with potentially fatal consequences.

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1. Captain, if the problem is not entered into the technical logbook.........then the aircraft does not have a problem.
2. And, if you have time to write the fault on a napkin and attach to it to the yoke.........you have time to write it in the tech log....see point 1.
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Re: Four-wheel maneuverability

Postby chornedsnorkack » Sat May 23, 2009 3:59 am

Note that a device that is limited to 60 degrees of steering CANNOT turn 180 degrees in its diagonal.

Turning 180 degrees in its own diagonal would require 4 wheel steering at 90 degrees.

Are the tugs able to travel at 30 mph in all directions including reverse and crabwise, or do they have lower speed limits when not straight ahead?
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Re: Four-wheel maneuverability

Postby expat » Sat May 23, 2009 11:45 am

Note that a device that is limited to 60 degrees of steering CANNOT turn 180 degrees in its diagonal.

Turning 180 degrees in its own diagonal would require 4 wheel steering at 90 degrees.

Are the tugs able to travel at 30 mph in all directions including reverse and crabwise, or do they have lower speed limits when not straight ahead?


Some can and some can't in my experience. However doing Vmax in a tug in any direction other than forward, lets say it can get interesting because if you going flat out and have to turn a corner or swerve unexpectedly and you are in crab mode, well it is going to end in tears and a large bill. Fortunately I learned my lesson from someone else making a very public and expensive cockup.

Matt
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1. Captain, if the problem is not entered into the technical logbook.........then the aircraft does not have a problem.
2. And, if you have time to write the fault on a napkin and attach to it to the yoke.........you have time to write it in the tech log....see point 1.
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