Posted 7/5/2010 4:07 PM (#52288 - in reply to #52282) Subject: Re: Two wheel drive vs one wheel drive
Posts: 4833 Location: Boise, Idaho
They have differentials just like a car.
If you want slow go for the 2 wheel drive. If not go for the 1 wheel dive rigs.
Posted 1/3/2011 9:29 PM (#55338 - in reply to #52282) Subject: Re: Two wheel drive vs one wheel drive
There are two types of 2wd that can be found on Ural and Dnepr. Earlier 2wd's had a differencial and full time 2wd. Later models had selectable 2wd with no differential. Full time 2wd could be driven on the street and had no drift/pull tendencies with application of throttle. Down fall was if either the pusher or sidecar wheel comes off the ground, you lose drive. For example, if you got the rig stuck with the sidecar tire up in the air off road...you would have no drive on the sidecar. On pavement, if you "fly the chair", the sidecar wheel rpm will spool down and when it makes contact with the pavement again, the torque as it grabs can damage the final drive (f.d.) guts. Parts are also very rare to non existent.
With the engagable 2wd models, you cannot engage the 2wd on a hard surface as it can damage the f.d.. When you do have the 2wd engaged, the rig will want to track in a straight line due to no differential. Assuming a hack on the right and 2wd engaged; left turns can be made easily...close to a 180 end swap with the sidecar wheel driving the hack around. Turns to the right however require a wide radius as you are now fighting the sidecar drive (which is attempting to track straight). The uninformed will make out that it is hard/impossible to turn with 2wd engaged. That's just B.S.
Single drive and 2wd engagable rigs (2wd disengaged) will pull right with throttle application (drag from non-driven sidecar wheel) and drift left with deceleration (cycle heavier/more drag than freewheeling hack). With the 2wd engaged the pull/drift is REVERSED...which can get you into trouble if you forget. Again, full time differential models do not have this tendency.
Single wheel drive is cheaper to purchase, cheaper to maintain, a couple mpg better and less maintenance than its 2wd counter part. 2wd is not slower (noticably) and has the same top end speed as 1wd.
Engagable 2wd is designed to be engaged and disengaged, "0n-the-fly". Attempting to do either at a stand still can damage the internals if you are ham-fisted. If you get stuck and cannot rock the rig a couple of feet back and forth...you'll have a difficult time engaging 2wd. You gotta plan ahead.
Whether you need 2wd is up to you. 90% of all conditions you would ride in a 1wd will do the job. 2wd IS NOT an ATV or 4X4...not even close. 2wd can get you into trouble if you are a moron with no common sense. A Ural/Dnepr rig is an underpowered 800lb farm tractor. 2wd is like owning a 4X4 pick-up. 98% of the time you never take it off the pavement...but that 2% of the time you need it...you are d@mn glad you have it.
Personally; unless you like hunting for parts or own a machine shop, stay away from full time 2wd. 1wd or 2wd (engageable) I'd pick a Ural over Dnepr as parts are easier to find; Urals are still made, come with a 2 year transferrable warranty (handy thing to have) and have a dealer network and larger support community. Run from kits unless you are a machinist and like smashing your finger tips with a mallet for fun.
Xpehbam did a good job of describing the difference between 2wd and 1wd rigs.
I have owned both. MT11 Dnepr of unknown vintage and 02 Ural patrol.
I have owned 8 other sidecar rigs also and several were for off road use.
Properly set up and piloted, a one wheel drive unit can take on the same conditions as a two wheel drive unit with a very few exceptions.
Some of the WW2 German rigs, notably some Zundapps and BMWs had the advantage of a two speed transfer case aft of the transmission. This allowed compound lower gears just like a jeep.
If Ural were to offer this feature I would again have one. It allows slow creep through very rough rocks that will bash the underside if traveled at ordinary idle. This causes much slipping of the clutch in modern rigs.
A compound gear would even be a great advantage on a one wheel drive in these circumstances.
I wish one of the manufacturers would offer a 650 to 800cc bike with a true granny gear for low and the rest in normal ratios for road travel.
Where I live the back trails are sharp lava and will tear the bottom apart if you cannot creep through some sections.
Posted 2/11/2011 7:13 AM (#56130 - in reply to #52282) Subject: Re: Two wheel drive vs one wheel drive
Posts: 1927 Location: San Isidro de Heredia, Costa Rica
you continue making me nervous.... these pictures cause my right hand to shiver and lift my hair in the neck.
And I do second Phelonnius about the extra low first gear as I had in the Unimog the first 2 were just for tough off road and on the road you started in 3rd or fourth.
The differential question brings into my mind the step-less free wheel high torque couplings I used to import for machinery. expensive, no light weight but superb and long lasting.
That lets open just the reverse to be done with a off the box gear set....hmmm, where to find that one?
Ah the swing arms and cardan shafts...I just last Friday had a close look at the Kawa shop....to the front drive of 4*4 mules....
looks interesting and makeable.
To william: first thing to adapt when I will get the 3rd wheel to the KLR will be an electricmotor to my 35meter hand winchet that I got out of an ancient Land rover....
That thing has history and shall tell more then "only" be used by an 86 year old man to pull logs out of steep rain forest slopes...He became over 95 and had his nick name well earned "Ron Ron" the hard wood that not even floats. (No saw or planer enters, only the sander and I had to drill and tap. Black market price in 1989 was 60$ per kilogram , The stair rail I had to prepare weighted about 70kg)--memories
Meanwhile my brain works and doesn't let me sleep, I better get to the technical college internate and fix more lathes....
School starts in 1 1/4 week and 18 lathes are still to fix.