DougC
April 29th 08, 01:56 PM
I am pondering building a tilting trike for some amusement. The idea I
came up with is shown here:
http://www.norcom2000.com/users/dcimper/assorted/inanities/recumbent/general/stuff/common.html
(alternate)
http://tinyurl.com/2nkdlr
In this diagram, the blue cross-bars are set on longitudinal pivots (red
dotted lines) so that the blue crossbars can tilt left and right, but
not turn left and right. The kingpins are set on ball joints so that
they will bend up and down on the crossbar ends, as well as turn left
and right. The kingpins are set with typical-upright bicycle-style rake
and trail (indicated by the orange and grey dotted lines) and other than
the two pivot points of the two blue cross-bars, there is no mechanical
connection to the kingpins at all. The control levers (purple) are
connected only to one of the cross-bars, allowing the rider to control
the tilt left-and-right. Because of their rake & trail, the front wheels
will roll where they are tilted--just like the front wheel of an upright
bike does when you ride no handed.
This type of tadpole-trike steering system presents a number of advantages.
-------
Given the length of time that bicycles have been around, it's a fair
assumption that anything that will work has already been tried a
half-dozen times already--it's just a matter of if anyone else was
watching at the time or not. So I was not real surprised when I found
one other vehicle that seems to use the same type of "free kingpin"
steering setup:
http://www.tiltingvehicle.net/technical.html
I don't understand everything this fellow says about his setup
(particularly this "low-speed steering cable" thing he goes on about)
but it looks to be the same basic concept. His steering is
hydraulically-operated, I assume to prevent suspension movement from
transmitting backwards into the steering controls. An unsuspended HPV
would have no need for external power to drive the tilting mechanism.
....This guy also makes the notable point that this type of steering will
not oversteer. If either end loses traction around a turn, the steering
will automatically drift into understeer.
-------
I have looked around for any HPV's with steering done this way (that is,
with un-steered kingpins) and have not found any. Has anyone seen any?
~
came up with is shown here:
http://www.norcom2000.com/users/dcimper/assorted/inanities/recumbent/general/stuff/common.html
(alternate)
http://tinyurl.com/2nkdlr
In this diagram, the blue cross-bars are set on longitudinal pivots (red
dotted lines) so that the blue crossbars can tilt left and right, but
not turn left and right. The kingpins are set on ball joints so that
they will bend up and down on the crossbar ends, as well as turn left
and right. The kingpins are set with typical-upright bicycle-style rake
and trail (indicated by the orange and grey dotted lines) and other than
the two pivot points of the two blue cross-bars, there is no mechanical
connection to the kingpins at all. The control levers (purple) are
connected only to one of the cross-bars, allowing the rider to control
the tilt left-and-right. Because of their rake & trail, the front wheels
will roll where they are tilted--just like the front wheel of an upright
bike does when you ride no handed.
This type of tadpole-trike steering system presents a number of advantages.
-------
Given the length of time that bicycles have been around, it's a fair
assumption that anything that will work has already been tried a
half-dozen times already--it's just a matter of if anyone else was
watching at the time or not. So I was not real surprised when I found
one other vehicle that seems to use the same type of "free kingpin"
steering setup:
http://www.tiltingvehicle.net/technical.html
I don't understand everything this fellow says about his setup
(particularly this "low-speed steering cable" thing he goes on about)
but it looks to be the same basic concept. His steering is
hydraulically-operated, I assume to prevent suspension movement from
transmitting backwards into the steering controls. An unsuspended HPV
would have no need for external power to drive the tilting mechanism.
....This guy also makes the notable point that this type of steering will
not oversteer. If either end loses traction around a turn, the steering
will automatically drift into understeer.
-------
I have looked around for any HPV's with steering done this way (that is,
with un-steered kingpins) and have not found any. Has anyone seen any?
~