Design Possibility, can or CANT be doneà
Design Possibility, can or CANT be doneà
(OP)
I’m kicking around an idea and want to get some comments as to its possibilities and maybe even its practicality.
Ok, I spent the weekend watching rock climbers, no not people climbing mountains but modified trucks, Jeeps and moon buggies (Purpose built 4x4’s). I seen more broken parts (drive line of course) then I see in my 15 years of being a mechanic (12 years ago). The other observation was the current mechanical drive line creates more limitations then I could count. This includes traction, clearance, power and the list goes on and on. Ok, Ok… Here’s my question.
It seems like the power of fluid could solve so many of these problems I have to investigate. Is it possible with the current technologies in fluid power (Motors, Pumps, Valves and Controls) to build the ultimate 4x4 or even rock crawler using 100% fluid power? Now I said “Possible”, let’s assume for the monument that money is no object (wouldn’t that be nice). Could one take say a Ford truck and replace the axels with Hydraulic motors (all 4 wheels), replace the transmission with a pump and the steering wheel with say joy sticks. Now I KNOW it’s much more complicated than that but for the monument think simple, what do you experts think is this something that could be done?
I’m not looking for any designs or direction at this point, just your thoughts!!
Ok, I spent the weekend watching rock climbers, no not people climbing mountains but modified trucks, Jeeps and moon buggies (Purpose built 4x4’s). I seen more broken parts (drive line of course) then I see in my 15 years of being a mechanic (12 years ago). The other observation was the current mechanical drive line creates more limitations then I could count. This includes traction, clearance, power and the list goes on and on. Ok, Ok… Here’s my question.
It seems like the power of fluid could solve so many of these problems I have to investigate. Is it possible with the current technologies in fluid power (Motors, Pumps, Valves and Controls) to build the ultimate 4x4 or even rock crawler using 100% fluid power? Now I said “Possible”, let’s assume for the monument that money is no object (wouldn’t that be nice). Could one take say a Ford truck and replace the axels with Hydraulic motors (all 4 wheels), replace the transmission with a pump and the steering wheel with say joy sticks. Now I KNOW it’s much more complicated than that but for the monument think simple, what do you experts think is this something that could be done?
I’m not looking for any designs or direction at this point, just your thoughts!!





RE: Design Possibility, can or CANT be doneà
Hydraulic motors at the wheels on farm sprayers – no axels
http://www.servspray.com.br/indexing.htm
http://www.servspray.com.br/indexing.htm
Electric wheel drive here $$$$$$ ??
http://w
RE: Design Possibility, can or CANT be doneà
Putting aside, for one moment, the inefficiency and the costs ETC...there is nothing that beats the power to weight ratio of hydraulics. It is possible to drive any piece of machinery with hydraulic actuators.
With the control technology available in modern valves it is possible to have infinite control, hydraulically or electronically.
This is a totally unbiased opinion of a Hydraulic Systems Engineer. Ask an Electrical Engineer and see if they agree.
Hydromech...
RE: Design Possibility, can or CANT be doneà
using hydrsostaic drive, you would also have dynamic braking
controls are the difficulty. Simiply teeing all together would be like an open differential-one wheel unloaded, all the oil goes there and spins 4x normal speed. and no traction.
We are currently working on a 4 axle drive vehicle that is expected to unload one axle at a time as the axles cross bad joints. Similar to driving 4 separate wheels of your truck. Nothing secret about the drive, its copied from previous industry technology. We will use 4 pumps, 4 motors, (1 pump drives one motor drives one axle. All four are separate from each other.) This of course gives no load sharing at all, if one pump/motor/wheel is fractionally more or less efficient, that drive pressure goes to 5000 and the others go into dragging at 5000 psi. In this case, there will be F & R pressure transducers on each PM package, and speed sensors in each motor. Overall software and controls will provide displacement (speed) control, the next inner loop limits by pressure to provide load sharing between the four drives, and the final inner loop is wheelslip limiting, i.e. don't exceed a couple percent slip no matter how unbalanced the pressure is.
HST are typically very stiff drives: touch of displcement and pressure spikes up to maximum. Several companies have 'automotive controls' that approximate a torque convertor drive: slushy with light throttle theen gradually increasing power and response with pedal motion. This allows maximum control and is used for maneuvering applications. perfectly suited for fine traction control.
k
RE: Design Possibility, can or CANT be doneà
John
RE: Design Possibility, can or CANT be doneà
With the correct pump, motor and torque hub ratio, I'm sure you could climb over anything.
Nick
RE: Design Possibility, can or CANT be doneà
http://www.e-traction.com/TheWheel.htm
I think there are a few other companies that make these sort of "wheel-motors" but i cant find them offhand
RE: Design Possibility, can or CANT be doneà
Dan Helgerson CFPS, AFPI, AJPP
www.cfpsos.com
RE: Design Possibility, can or CANT be doneà
htt
RE: Design Possibility, can or CANT be doneà
RE: Design Possibility, can or CANT be doneà
Dan Helgerson CFPS, AFPI, AJPP
www.cfpsos.com
RE: Design Possibility, can or CANT be doneà
http://www.wavecrestlabs.com/index.html
RE: Design Possibility, can or CANT be doneà
Other info that i have been reading is saying that the gear trains and such max out at 50% eff. I think i was reading one of these as companies as saying that running one as a motor driving a second as a generator they were getting 80% system eff.
RE: Design Possibility, can or CANT be doneà
I finished my BSME after the oil slump in the 80's and have been designing hydraulic systems since. Hydrostatic drive systems are gaining more popularity with off road equipment as well as in fan drive systems and high tech transmissions (hydrostatic and powershift combined). I think a hydrostatic transmission system installed on any off road vehicle has advantages over conventional systems.
The best system I ever used was a powershift transmission driven by a hydrostatic motor. I crawled over some of the steepest sand dunes and rock structures ever imaginable and was able to maintain good traction.
RE: Design Possibility, can or CANT be doneà
Your biggest problem is down to size, wheel motors like the Hagglunds Dennison viking range are quite huge, but then you could go onto the Vickers motors, or Staffa, or go as far as the german manufacturers, Brueninghaus, Rexroth, and Beauringers.
If you have any links with deep shaft mines, you could pick up some ideas from drawings supplied with Dosco machinery, or Mindev, BJD, Fletcher Sutcliffe and Wilde,
But basicaly speaking, the idea you had originaly, will work, can work and has already been proven to work, now, when it comes to areas like rock climbing or rough terain, then you have to think about putting your wheel motors on floating floating anchors, and these would have to be actuated by hydraulic cylinders that would be fed by a pressure sensitive control, thus allowing movement in both up and down to compensate the weight displacement of the vehicle, in short and elaborate shock absorber.
in truth, if you ever get a unit built, i would love t see it
RE: Design Possibility, can or CANT be doneà
RE: Design Possibility, can or CANT be doneà
RE: Design Possibility, can or CANT be doneà
I design and test aircraft hydraulic systems for a living.
I would love to share these ideas with anyone.
RE: Design Possibility, can or CANT be doneà
The only obvious issue I can see is using a flow divider to drive the wheels.
Going in a straight line...great, turning corners...that may be a problem.
When turning, the inside wheel will want to turn at a different speed to the outside one. Because its moving around a smaller arc it will want to go slower. The flow divider will keep both wheels turning at the same speed.
The handling of the buggy could be scary. But then again...that may be just what you are looking for???
Also, if the buggy has one drive wheel off the ground the flow divider will intensify the load in the motor that is still driving the buggy. That again may not be a problem for you, but it could potentially force the wheel of the buggy.
I wish I could tell you the best way to do it, but I have little experience with drive systems like this...sorry!
Best of Luck
Hydromech
Hydraulic Systems Engineer
RE: Design Possibility, can or CANT be doneà
Ian
RE: Design Possibility, can or CANT be doneà
I have started collecting tubing, hoses, minor valves, flow controls solenoids, needle valves, I have a few actuators for suspension and steering. I still have to get the wheel motors and pumps. I think I will drive the pumps off a standard piston engine/funk gearbox until I can afford/justify a turbine. I also have the bladder (reservoir) and heat exchanger that are going to be used. I am going to put the bladder inside of a tank, and pressurize the tank with shop air for positive system return/suction pressure. I may be able to get away with a bootstrap reservoir arrangment.
Another arrangment would be to utilize one pump per wheel motor.
This is obviously still in work, slowly collecting pieces and parts as I go. I have the frame designed in Cad, but can't finalize the design until I have all the parts I am going to use. Thanks for all the feedback and contructive critisicism.
This is a really great site.
Tad
RE: Design Possibility, can or CANT be doneà
You haven't mentioned a budget or where you are located-during the mid 1970's International Harvester made several models of combines that used a D414 diesel motor and most were hydrostatic drive with a C-faced mounted Eaton or Sundstrand pump(this was contrary to the popular design of belt drive pumps at this time). The DT414 was rated at 175 hp but was capable of a lot more-some tractors used this same basic motor and it was used a lot for hotrod pulling tractors. There are some of these combines still floating around -some with the RWA-Mud Hog. As these models are 30 plus years old they are not worth a lot to todays farmers and might furnish you with a power plant,pumps and wheel motors along with a lot of other parts you might need. Good luck ,Maytag
RE: Design Possibility, can or CANT be doneà
I ride Observed Trials motorcycles, and last weekend rode an event in Northern MN at a state off-highway vehicle park made from an abandoned open pit iron mine. Two square miles of blast and haul rock, from tailings to rocks the size of a car, in piles up to 300 ft tall. There are endless trails for motorcycles, ATV, Jeeps, etc. The ATV people blasting through mud doesn't interest me at all, but the rock crawlers are fascinating to watch. Trials riders have a lot in common with the crawlers: precision technique, control, traction, etc. vs. just throttle and blast through.
There was plenty of hp present, but generally they are well engineered and technical machines. Looks like a ball, but expensive!
keep us posted
kcj