Drysdale 2x2x2- 2WD Overview

20 Jun 2015 | kaituhi: | Off i runga i Drysdale 2x2x2- 2WD Overview
Suzuki Falcorustyco
Suzuki Falcorustyco

2WD MOTORCYCLE OVERVIEW

Two wheel drive motorcycles can basically be split up into two broad groups; te hunga ki te puku pūkaha i te tikanga o mekameka ngahaú ranei, me te hunga e whakamahi puku waipēhi whakamahi pressurized inu pērā i te 2x2x2 Dryvtech. Ka rite ki ki tetahi wehenga i hoahoa auraki, aua paihikara hāngai kaha i runga i huira ngā kiia ana he atu 'angitu', ahakoa tei te whakamāramatanga o taua kupu te nuinga i runga i te whāinga o te kaupapa.

He kua he torutoru whakaaro 2WD i roto i nga wa tata tino kua i whakanohoia 2WD i runga i te mahere no ratou te mahi rite te pahikara tikanga, engari he iti pai. Who was it in the GP world who said The bike that wins this year will the bike that won last year, plus 5%?


Mechanical two wheel drive motorcycles are by no means a new idea- the earliest on record was a 1924 Raleigh that was converted to 2WD for trials events. The later 1937 FN was actually quite a good design with ‘only’ 2 chains required to drive the front wheel- the girder front forks of the day making this possible.

Unlike the majority of more recent mechanical 2 wheel drive motorcycles, the FN was reputed to have run a fixed drive to both wheels- made easier by bikes of the day running the same tyre sizes front and rear. More recent mechanical 2 wheel drives all seem to run a principle common in ‘4 wheel assist drivetractors- that is to gear the front wheel(s) 5% slower than the rear through a ‘sprag clutch’ (a one way drive). This system is becoming quite well developed mainly because it’s relative simplicity allows for the construction of an experimental bike (usually by a so-called ‘backyard inventor’) without the need for a large investment of funds.

In this system the front wheel is ‘pushedalong in the normal fashion when the rear tyre is getting full traction and then the front wheel drives ‘fully’ (engari 5% slower) when the rear wheel achieves 5% slip. It seems this has a more natural feel for motorcyclists than more complex constant drives with torque splitters and viscous couplings as used in rally cars. This improved ‘feelis apparent not only under power, but also under braking where the rider can still steer the bike by dragging the rear brake coming into a corner as with a 1 wheel drive- this doesn’t affect the front wheel rotation at all.

Hydraulic drive (and steering for that matter) is less common, the only known example to use fully hydrostatic drive to both wheels other than the Dryvtech was an Oddball Suzuki concept bike called the Falcorustyco in the mid 80’s, though it is not known whether this was a working bike or whether it was merely a mock-up built for the Tokyo motorshow. More recently there have also been several ‘hydraulic assistsystems where a standard chain drives the rear wheel and a low powered hydraulic system drives the front, up to and including the 1998 Öhlins enduro bike.

All these systems have their advantages and drawbacks, mechanical drives have at least three drive chains (usually more)- we all know how fun they are to lube, adjust and replace. Mechanical systems also have limitations on steering lock, gearing hassles and front suspension design problems, while the hydraulic system is undoubtedly expensive and heavy when using industrial components.

The hydraulic drive bike also cannot be pushed around with the engine stopped without a bypass valve between the pump and motor/s. Interestingly a sprag clutch equipped 2 wheel drive is also difficult to push backwards- but for different reasons to the hydrostatic drive. Basically the sprag clutch ‘engageswhen going backwards and you effectively have the front wheel trying to drive the rear wheel 5 % faster, but both are on the same ground and therefore going at the same speed.

The tyres can heard scrubbing when pushing backwards on a hard surface. The first 4WD sportscar- the Jensen 4WD used a special mechanism to disengage the ‘wheelspin limiterduring reverse. I often wonder if this was part of the first design or if it was discovered the first time they tried to reverse the prototype.

But these problems are merely small hurdles that must be overcome in the quest to reap the benefits that 2WD can offer us, see the Ride Impressions page to hear what the end result is actually like.

tuhinga Interesting

tūtohua rite:

Ētahi atu tuhinga o te kāwai "Suzuki":

Translation
 Whakatika Translation
To tatou hoa
A pee i tatou
Whakapā mai
To tatou hoapā

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