hydraulic pump/motor replacing tailshaft?

[derangedrover]

Hydraulic guru's...

What would you need to replace a tailshaft with a hydraulic pump and motor arrangement?

Could it be done without a big reserviour and cooler? What sort of pump/motor, line size etc would be required? Parameters would be approx. 5000rpm max speed, max torque at pump say 10k ft/lbs.

What sort of $?

Thinking it might solve problems of too short a shaft, driveline angle issues, or where you need to reverse the direction of rotation from gbox output to diff input, like in buggies with rear mount engine.

Cheers
Daryl

[bazooked]

how deep are ur pockets?

[rlaxton]

Hi,

I don't think that this is going to be practical for a number of reasons.

1. Availability of high speed hydraulic motors. Most of the really big hydraulic motors are high torque, low speed.
2. It will be heavy.
3. The oil flow will blow your mind.

For example, an 11ci motor that can do 2400 rpm @ 2000psi typically weighs around 40kg. Not the best thing to add to you axle and even this is only putting out around 115 hp. You also need oil flow of around 110 gpm (>400L) per minute which would require pipes about 2" across that would be none too flexible.

While there are plenty of vehicles that use hydrostatic transmissions (which is what you are talking about). None that I know of would handle anything like the levels of power that you would need without weighing a lot more than a simple tail shaft with a few cardan joints.

It might just be possible to build a buggy with four big wheel motors but it would probably be a crawler only.

Richard.

[edit]
P.S You would also definitely need a cooler in your application. That, and applying the rule of thumb for reservoir volume, a 400L oil tank.

[mickyd555]

doesnt a skidsteer work on this principle??? maybe you would have to use that idea to turn.........which would be in your favour i supose ie: tighter turning circle








and ya could put a bucket on the front and just dig through the obsticle if ya cant get over it

[twinnie]

what about torque? surly these motors are very high torque, so with high gearing it should work? but you will need a cooler and it will suck alot of power

Matt

[Shadow]

yeh, way to expensive heavy and expensive.

did i mention expensive.


have thaught of a smilar thing myself, although i thaught the best way would be to fabricate your own beam axles, have a drive for each wheel driven through either direct drive, or with a chain so you can get a "portal" type setup for clearance.

would be a matter of getting an old bobcat or something, stripping it for everything, reconditioning it all/replacing broken stuff.

would be a very cool setup. Doubt youd get it to go faster than bout 40km/hr though. WOuld be awesome for a rockcrawler, you could rig up a hydraulic proportioning system so it acts like all 4 wheels are locked, and then youd have the ability to skid steer etc (LH wheels in reverse, RH wheels in forward :D:D:D) 360degrees on the spot, thats better than any rear disconnect

[Shadow]

what about torque? surly these motors are very high torque, so with high gearing it should work? but you will need a cooler and it will suck alot of power

Matt

problem is diff gears are traditionally "tall"

whats the lowest diff gears you can get for your vehicle.

Id suggest that even custom diff gears the lowest they will go is about 4:1, so to turn 40" tyres at 100km/hr, with 4:1 diff gears you need a wheel RPM of about 530, which is a input RPM of 2,100 ish.

a hydro motor running at that speed is going to be seriously expensive, and seriously uncommon. running a 1:1 ratio would definantly be possible. But no diff runs 1:1, (that i know of lol)

[twinnie]

mmm i just thaught of some thing! you know those realy big trains. well they run like huge gensets for the motors that drive the wheels so surely thats a posible set up mabey not to high cost. you can get huge torque from stop too.

and now the down side, water crossings ZAP!

and it might lead to a high unsprung weight.

Matt

[Shadow]

mmm i just thaught of some thing! you know those realy big trains. well they run like huge gensets for the motors that drive the wheels so surely thats a posible set up mabey not to high cost. you can get huge torque from stop too.

and now the down side, water crossings ZAP!

and it might lead to a high unsprung weight.

Matt

would be too heavy id say. not that a hydro setup would be lkight tho.

[frp88]

my cousin has just upgraded his ox winch to go from 1m a minute to about 10m a minute(not tested) we will next weekend
he has spent over $1000 and did the entire job himself hyd. is good but big$

["CANADA"]

check out a EWP drive setup...all hydro...or a big 4ws 4wd forklift on portals

[440 BB]

weight for a buggy wouldnt be too bad, only way to do it would be a hydrostat setup, direct driven variable displacement pump (ie no gearbox) to either individual wheel motors either series linked or fed through a good flow controll setup ,or 2 motors attatched where the tailshafts would be . would be pricey but it gives all the reduction you want, fully variable transmission with no shift points, and the possibility of individual controll of drive motors. also the cost might not be too bad when compared to the cost of upgrading diffs for huge tires plus lockers, and it gives you huge ground clearence (better than portals), can put your engine anywhere. the main cost would be finding a useable second hand variable displacement pump big enough.

[SierraDan]

http://www.pirate4x4.com/forum/showthread.php?t=763311" onclick="window.open(this.href);return false;

[chunderlicious]

weight for a buggy wouldnt be too bad, only way to do it would be a hydrostat setup, direct driven variable displacement pump (ie no gearbox) to either individual wheel motors either series linked or fed through a good flow controll setup ,or 2 motors attatched where the tailshafts would be . would be pricey but it gives all the reduction you want, fully variable transmission with no shift points, and the possibility of individual controll of drive motors. also the cost might not be too bad when compared to the cost of upgrading diffs for huge tires plus lockers, and it gives you huge ground clearence (better than portals), can put your engine anywhere. the main cost would be finding a useable second hand variable displacement pump big enough.

plenty of pumps big enough for a good price, get on ebay, fitting to an engine would be easy an LS motor (like the pirate buggy) should be able to spin a fair size pump. have a constant throttle setup or if your smart a load sensitive throttle and run joysticks instead of a steering wheel. left stick for forward reverse on the left side and rear steer and right stick for right hand forward reverse and front steering.. wouldn't be quick but could potentially be competitive in rock crawling.

the hard part would be getting it in at a good weight, a good tank that could have enough capacity to supply it all and run at ridiculous angles etc. cooling wouldn't be that hard as there are plenty of options out there for this stuff nowadays and you can put them anywhere on the vehicle really.

its a lot of hassle really. be 10G in hoses alone i would recon.


as for electric drive motors..... if they are anything like the large ones in haul trucks etc. then they are laggy, till the revs get up high enough etc.

[vanbox]

my cousin has just upgraded his ox winch to go from 1m a minute to about 10m a minute(not tested) we will next weekend
he has spent over $1000 and did the entire job himself hyd. is good but big$

Keep us posted. I have one im always looking to get more speed and capacity