# Transmissions automatic,standard or Hydrostatic



## Efiero (Feb 7, 2009)

*Hydrostatic drives* 
Hydrostatic drives are widely recognized as an excellent means of power transmission when variable output speed is required. Typically outperforming mechanical and electrical variable-speed drives and gear-type transmissions, they offer fast response, maintain precise speed under varying loads, and allow infinitely variable speed control from zero to maximum. 
Unlike gear transmissions, hydrostatics have a continuous power curve without peaks and valleys, and they can increase available torque without shifting gears. But despite the superior performance of hydrostatics, a major drawback has been higher cost compared to their mechanical counterparts. 
Manufacturers, however, continue to boost performance levels, produce smaller and lighter packages, and offer advanced electronic controls. These factors now make hydrostatics an economical choice for many applications. 
A basic hydrostatic transmission is an entire hydraulic system. It contains pump, motor, and all required controls in one simple package. Such a system provides all the noted advantages of a conventional hydraulic system -- such as stepless adjustment of speed, torque, and power; plus smooth and controllable acceleration; ability to be stalled without damage; and easy controllability -- with the convenience of single-package procurement installation. 
Early hydrostatic transmissions were intended primarily for low-cost applications such as farm equipment and garden tractors. But improved designs -- particularly in controls -- have made these transmissions suitable for a broad range of applications. 
As a result, light-duty units (less than 20 hp) are being used on equipment such as lawn tractors, golf-course maintenance equipment, and small machine tools; medium-duty units (25 to 50 hp) on skid-steer loaders, trenchers, harvesters, and other such vehicles; and heavy-duty transmissions (approximately 60 hp and higher) on agricultural and large construction equipment. 
Part of the reason for the increasing attractiveness of hydrostatic transmissions is improved design of pumps and motors -- particularly higher flow and pressure ratings in a more compact package. For example, several years ago, most pumps could be expected to deliver about 0.125-gpm flow per pound of pump. Currently available pumps deliver about 0.5 gpm/lb, a 400% increase. Similarly, older motors provided about 0.5 hp/lb of motor; new motors provide about 2.5 hp/lb. 
*Performance:* Hydrostatic transmissions are commonly available with at least three standards of output performance:

Variable-power, variable-torque transmissions are based on a variable-displacement pump supplying a variable-displacement motor. They can provide a combination of constant torque and constant power. These units are adjustable, flexible, and expensive.
Constant-torque, variable-power transmissions are based on a variable-displacement pump supplying fluid to a fixed-displacement motor under constant load. Speed is controlled by varying pump delivery. This is considered the best general-purpose drive, with wide speed ranges, up to 42:1, and simple controls.
Constant-power, variable-torque transmissions are based on a variable-displacement pump with a power limiter, driving a fixed-displacement motor. The forte of this unit is efficiency, but speed range is usually limited to 4:1.
*Drive configurations:* Hydrostatic transmissions usually take one of two general configurations, split or close coupled. A split transmission consists of a power unit with the hydraulic pump, heat exchanger, filters, valves, and controls mounted on a reservoir. The hydraulic motor is remotely mounted and connected to the power unit through hose or tubing. Split transmissions are typically used in heavy-duty applications because they offer wide flexibility in configuring a system for the most efficient use of space or best weight distribution. 
Integrated, or close-coupled, transmissions have a hydraulic pump and motor that share a common valving surface. This arrangement provides an extremely short oil-flow path, eliminating high-pressure oil leaks either to the reservoir or to the environment. A cast casing or housing provides a self-contained oil reservoir, structural support for the rotating elements, and heat dissipation. They are usually bolted directly to a mechanical differential axle to form a hydrostatic transaxle. Close-coupled transmissions are typically found in light-duty applications, where tight space constraints require compact units, while high-volume production mandates easy assembly. 
*Transmission sizing:* Hydrostatic transmission size normally is based on the corner horsepower of the work function. Corner horsepower is the product of the maximum force and maximum speed required by the function, even though these two conditions rarely occur simultaneously. Corner horsepower for vehicle propulsion is
_Hc = ( Ft * V ) / 3,600n_ 
where _Hc_ = corner horsepower, kW; _Ft_ = maximum vehicle tractive force, N; _V_ = maximum vehicle speed, km/h; and _n_ = final drive efficiency, %. 
Transmission corner horsepower, _Ht_, is the product of maximum output torque (generally at a specified maximum pressure) and maximum output speed: _Ht = ( Tt * N ) / 9,550_ 
:where _T_ = theoretical torque at maximum system pressure, N-m; _t_ = torque efficiency, %; and _N_ = maximum transmission speed, rpm. 
Initial transmission selection is made by comparing the results of these calculations. Selection is refined by considering the effects of duty cycle, final-drive ratio, rolling radius, primer-mover speed, and design life. *Electronic controls:* Control capabilities for hydrostatic transmissions have advanced from simple remote electrical actuators to packages that offer complete optimization of machine performance. For example, electronics on paving equipment not only controls the transmission, including speed and rate of acceleration and deceleration, but also steering, paving height, rate of material flow, road crown, slope on curves, and so on. While not currently economical for every application, proportional controls offer a reasonable payback in most traction drives and propel systems through fuel savings and increased productivity. Acceptance will quicken when the added benefits in addition to primary control are recognized. One such feature is performance monitoring, another is system diagnostics -- relating when servicing is needed, when failure is imminent, or where a failure has occurred. Such features are relatively easy to add into software because many of the variables needed are already measured for control.


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## CBOY (Feb 13, 2009)

A real newbie question here. Could a hydrostatic transmission allow one to run their electric motor at a constant speed, or with minimal speed changes, thus eliminating the need for an expensive, high end controller? And would such a setup be effective, or would it defeat the the great torque advantages of electric.

We havy hydrostatics on our lawn tractors and we basically just run them wide open and control the speed of the tractor totally with the transmission stick.


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## Efiero (Feb 7, 2009)

yes you could run the motor at let say 6000 rpm and control speed through the hydrostatic drive with a variable dispalcment pump go to this site they will tell you more i bought the dvd they have .i would like to know why you cant just put full voltage to the motor on start up some say it will fly apart it must be the acceleration 
http://www.hydraulicinnovations.com/


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## bblocher (Jul 30, 2008)

Efiero said:


> yes you could run the motor at let say 6000 rpm and control speed through the hydrostatic drive with a variable dispalcment pump go to this site they will tell you more i bought the dvd they have .i would like to know why you cant just put full voltage to the motor on start up some say it will fly apart it must be the acceleration
> http://www.hydraulicinnovations.com/


With full voltage it will rev far beyond the RPM limits of the motor. It's just like a gas engine. They have rev limiters because they would also destroy themselves with no load to govern the RPMs.


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## Tom Thomson (Jun 11, 2008)

Efiero
You have no doubt noticed that automatics and hydraulic systems usually have coolers. Can you afford to throw away energy?
tommyt


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## Efiero (Feb 7, 2009)

yes in a normal auto you allso have a torque converter with slipage and creats heat and the torque converter is not needed with the electric motor and a hydrostatic drive uses a veriable displacment pump how that works is by vareying the stroke of the pistons from zero stroke to max stroke all thoe i like the hydrostatic drive i think the best cheapest way is a 3 speed auto trans with an electric external pump and a direct drive for it


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## tj4fa (May 25, 2008)

Substitute an electric motor/battery pack with this hydrostatic drive concept linked below (or not) and maintain pressure on the system maybe adding a battery pack driven motor driven flywheel/pump combination sorta like I mentioned in your other thread.

I wouldn't mind trying to use a hydrostatic system on something small like my wife's '93 Civic replacing the 4cyl ICE with a very small ICE powering one or two of the rear wheels with hydraulic wheel motors. 

Maybe one hydraulic wheel motor and using an electric wheel motor to drive the car in an electric hybrid mode especially if the drive system needs a lot of initial start up torque.

From the specs at the website, it looks like each hydraulic wheel motor puts out a lot of hp.

One plus for this hydrostatic system is the hydraulic wheel motor(s) help maintain the pressure in the accumulator tank on braking (hydraulic REGEN).

http://www.valentintechnologies.com/concept/default.asp

Also check out these websites:

http://fuel-efficient-vehicles.org/FEV-Hydraulic-Car-Don-Banky.php

http://fuel-efficient-vehicles.org/FEV-Hydraulic-Dragster-KCMo.php


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## Efiero (Feb 7, 2009)

thats a cool idea just need the motors to run on a presure switch to turn on when it gets to low


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## Efiero (Feb 7, 2009)

I got thinking about that with the acumulator you could duble your range with it this is what i am thinking is when you charge your batteries the pumps would run and charge the acumulators so when you first started out it would just run off the accumulator for x amount of miles then when it got down to a certin pressure your pumps would kick in just need accumulators big enough to store enough power to go like 50 miles at lets say 65 MPH


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## Duncan (Dec 8, 2008)

Hi Efiero,
Hydraulic accumulators store energy by pumping oil into a pressure cylinder and compressing nitrogen in an envelope in the cylinder.

50 miles at say 200watt hours per mile - 10 Kw hours - 3600 x 10,000 joules

Energy in accumulator = volume x 1/2 x max pressure

2 cubic meter accumulator at 36,000,000 N/m2 would do, 

that is not bad - = 360 atmospheres, some accumulators do run up at these pressures

2 cubic meters - not so good - 
a big accumulator would be 20 litres 1/100th of this size

A 2 cubic meter accumulator would weight about 2 tonnes

An accumulator would be good for rapid acceleration or regenerative braking - could have enough energy for 5 miles

This system has been used in buses and gave 30% improvement in fuel consumption


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## Efiero (Feb 7, 2009)

well i thought that it might be to big but you could use one to give like 30 seconds of speed right and have regen braking to it could make the car realy quick and give it a higher top speed for a short time


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## mkralovec (Jul 1, 2009)

I have done a lot of thinking about this setup, and this is what I plan on implementing in my 1960 Jaguar Mark IX electric conversion project. 

The system that I have in mind begins with a set of batteries, driving a 7" DC electric motor. I plan on having the DC motor attached to a fixed displacement hydraulic pump through a chain drive, with a gear ratio set to allow the electric motor to run at its maximum efficiency while allowing driving the pump at its maximum efficiency. This motor can be running continuously. 

I plan on having a 5 gallon hydraulic accumulator that is filled by this pump being filled continuously, and then a variable displacement hydraulic drive motor attached to the differential of the car. The previous poster is correct that the 5 gallon accumulator would not allow anyone to drive very far, but it would allow for a transient burst of acceleration for approximately 30 seconds. I have done the calculations based on an eaton ME100 motor, and a 5 gallon accumulator, and in theory this system will work. 

While you are sitting at stoplights, or cruising along slowly and not using very much power, the electric motor will be driving the pump and filling the accumulator. When accelerating, the accumulator will be decreasing in pressure, providing power to the rear wheels.

Has anyone ever done this before? I would love any advice, ideas, help or information that anyone has. Please check out the project at electricjaguar.blogspot.com

Mike


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## bbbowden (Apr 13, 2009)

From earlier in the thread:

www.hydraulicinnovations.com

They built a diesel/hydraulic motorcycle that gets 70 MPG.


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## few2many (Jun 23, 2009)

It all sounds like alot of added this or that, more motors and pumps and linkages to pull power. I like the idea of just using a the hydraulic pump thats already in the front of the tranny. Eliminate the torque converter, use a circle track race type coupling, and either idle the motor with a few hundred rpm(ice engines idle high just to keep running) or have a 2-4 quart accumulator. I would use the GM 700r-4, only because im familiar with its operation. This can probably be done with just about any type of auto. You wont have the slip or heat build up of the tc, but it needs a hollow cavity as the tranny wants to flow fluid into and out of the tc.


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## Electric Car-Nut (Jul 5, 2009)

Hello,
There are different characteristics to different configurations of electric motors. No, I don't mean AC or DC. I am referring to Series or Parallel The series is most commonly seen in conversions. it is characterized by HIGH stall or slow rpm torque. and a wide rpm range of operation in actual fact the current rises with higher rpm so speed never stops accelerating until the load holds it back or the centripetal forces tear the armature apart
However there is also a Parallel configuration DC motor. It has somewhat less torque at stall or slow RPM, And the RPM rises to a designed RPM and stays at that RPM even if there is no mechanical load attached ! This motor could be used with a Hydrostatic or other Constantly Variable Ratio Transmission like those used in several smaller modern autos with no Controller except a on/off contactor with perhaps 3,4,or5 voltage levels from switching the batteries in series and parallel with contactors and using a "CVT" to set exact cruising speed. Parallel wired DC motors are used in electric hand tools like drill motors and saws. (Even though they are run on AC and might use a "Light dimmer circuit" as a crude speed control.)


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## Electric Car-Nut (Jul 5, 2009)

Mkralovec, Your drive sounds a lot like the acceleration assist used in the newest United Parcel Service delivery vans, but they are still using small diesel engines.


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## gor (Nov 25, 2009)

mkralovec said:


> I have done a lot of thinking about this setup, and this is what I plan on implementing in my 1960 Jaguar Mark IX electric conversion project.
> 
> The system that I have in mind begins with a set of batteries, driving a 7" DC electric motor. I plan on having the DC motor attached to a fixed displacement hydraulic pump through a chain drive, with a gear ratio set to allow the electric motor to run at its maximum efficiency while allowing driving the pump at its maximum efficiency. This motor can be running continuously.
> 
> ...


variable displacement motor still doesn't gives wide torque/rpm range (only 30% (?)change) - so transmission still might be needed;
motor with parallel/series switch - there been comments - in DIY vehicle application they wasn't effective in high rpm 
Mike, how hydro accumulator and el. ultracapacitor systems compare?
p.s. 100ci motors (eaton me100 range) used on small walkbehind mowers (direct drive, each wheel), for heavier machines 700-1400 lbs, it takes at least 180-240ci


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## erth64net (Jan 9, 2011)

I see the discussions died off a few years back...did anyone here build a hydrostatic EV?


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## Electric Car-Nut (Jul 5, 2009)

erth64net said:


> I see the discussions died off a few years back...did anyone here build a hydrostatic EV?


I have not seen one. My most common configuration now in building a conversion is for standard sedans and smaller vehicles use no transmission at all just the 4.11 gear in the differential. For larger like one ton trucks and larger I use a manual truck transmission for higher rpm and reduced ampere draw, therefore increasing range 10 to 20%. I haven't done any larger than 1.5 ton...as yet, but I might next year. for converting off road 4 X 4 vehicles I use the 4::1 low range in the transfer-case off road and shift to 1::1 on paved roads. It works well for Jeep products...with no transmission however if I was building one for rock-climbing in the mountains I would possibly include a 4-speed manual for higher rpm and better motor survival. 
Someone commented the public wants a universal vehicle, but I see many pickups towing a very specialized vehicle on a trailer on their way to have fun off the road . Why can't off road vehicles be ELECTRIC? They don't need to have a 300 mile range, carry them around on a trailer! Small battery pack, lighter weight motor than the ICE The competitors will call it UNFAIR because it would work so much better...


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## Electric Car-Nut (Jul 5, 2009)

WOW four years laiter and we are (Some of us still) debating transmissions. Well my posting is still valid but since then "www.KANSASEV.com" has opened. they take the two speed planetary automatic and put a "Race Kit" in the valve body and skip the torque converter. Go look at the pictures and description on the web page. I like the concept but I feel they like it too much as their price is twice as much as I have been quoted for a similar conversion giving two select-able forward speeds, one reverse, neutral and park with an external electric pump to eliminate idling. Read their description and look at the pictures and have a local transmission shop that does racing work build one for you. And save much on freight...Or buy one from them, they are nicely done and you won't have to reverse engineer one. the Power Glides were even used in big motor homes and they are great transmissions. Built right they are close to "Bullet Proof." Drag Racers still use them at over 1,000 Horse Power.


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## John Metric (Feb 26, 2009)

Here is the four speed transmission we run at Lonestar EV Racing & Performance. Lenco/GV


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## Electric Car-Nut (Jul 5, 2009)

John Metric, WOW, what a lengthy drive! The two coupling adapters also look like interesting designs. Why the two extra modules in place of a longer drive shaft? what ratio are the four forward gears? do you find with the twin series motors that the wide power band is the four different gears actually needed? Also I see no clutch (no bell housing) and we will all be wondering if having no clutch slows down shifting and hurts your lap times? Part of the reason for using the Power Glide is the planetary gearing set-up so all gears are in constant mesh and faster shifting is easy but I am not very familiar with the transmission you show, is it planetary or synchronized gears? In a clutch-less design which do your customers and yourself prefer? Sorry about all the questions but we all seek your insight. Thanks for showing the great picture too.


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## mizlplix (May 1, 2011)

You are preaching to the choir:

http://www.diyelectriccar.com/forums/showthread.php?t=59659&highlight=1930


http://www.diyelectriccar.com/forums/showthread.php/building-ev-powerglide-transmission-77105.html

My car is now running direct drive with no transmission, not because of any fault of the powerglide, but a capable AC motor came available.

The only down side of a race prepped glide is the down-shifts. Never down-shift when the vehicle is moving because it causes loss of tire compliance. (A screeching noise) They are very abrupt when downshifting. 

Miz


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## John Metric (Feb 26, 2009)

Electric Car-Nut said:


> John Metric, WOW, what a lengthy drive! The two coupling adapters also look like interesting designs. Why the two extra modules in place of a longer drive shaft? what ratio are the four forward gears? do you find with the twin series motors that the wide power band is the four different gears actually needed? Also I see no clutch (no bell housing) and we will all be wondering if having no clutch slows down shifting and hurts your lap times? Part of the reason for using the Power Glide is the planetary gearing set-up so all gears are in constant mesh and faster shifting is easy but I am not very familiar with the transmission you show, is it planetary or synchronized gears? In a clutch-less design which do your customers and yourself prefer? Sorry about all the questions but we all seek your insight. Thanks for showing the great picture too.


Ratios are 1.56, 1.00, 0.78, 0.61 (we can build one for you!!http://www.ampahaulic.com/)
Of course, do you need to tame 1500ftlbs of torque or go 200mph?
What you see is a Lenco Two speed case on front (1.56, 1.00) http://lencoracing.com/
Then the reverser with nuetral, 
Then a Lenco to Gear Vendors http://www.gearvendors.com/ Adapter, then a GV "Multi" racing unit which is not on the website only in the hard copy brochure they send out, then a GV to GV adapter, then a "normal" 30,000lb RV overdrive called a TH475 (heavier than the normal TH400)
It is direct drive, no torque converter or clutch in there.
It is pneumatic shifting on the Lenco (which we actually use Nitrous, so we like to say we are the first EV to run on Nitrous!)
It is electric shifting on the two overdrives. I have a push button for 1st to 2nd and a pull shift from a two position boat choke switch for 2nd to 3rd and 3rd to fourth.
Shifting is nearly instant. All three are planetary gear systems with clutch packs. Lenco good for about 2300HP, the GV good for about 1200HP.

As far as are they are needed......
We run a 1.30 60 foot time on a 2450lb race weight car, that translates into a 0-60 time of about 1.8seconds.
As far as the second overdrive, we also run the Texas Mile and we would definitely need it for that at around 200mph. But on the drag race strip the second overdrive is marginal improvement until we reach about 150mph in the 1/4 mile, which I haven't done yet. We hope to get there in the next month or so.
We never run the motors above 3500rpm and in the 1/8th mile we don't run above 3100rpm. We try to keep it in the power band. But of course we are not driving for fuel effiiciency, we are driving for acceleration.

Check out my build links under my name below for more pictures of DC Plasma and Assault&Battery. The batteries, controllers, contactors and motors are interchangeable between the cars.

Planning it over I would have dropped about $300 more bucks to get the shorter overdrive multi adapter, I would skip the oil seal on the lenco and shortened that 4.5" offset between the motor and the Two speed to 1.5", and we could take some length out of the motor to motor adapter, overall saving about 12". But, this all fits in a stock wheelbase Miata MX5, with an additional 14" double ujoint and slip driveshaft and has plenty of room up front for twin blower motors and other things means it isn't "too" long.In fact, I think the picture makes the system look extraorindarily long due to the small diameter motors. Here is my system next the powerglide I pulled out. If I would have used the shorter adapters I think it would be quite competitve with the long tail powerglide.


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## Electric Car-Nut (Jul 5, 2009)

WOW, thanks for the detailed Information, I found it very interesting. I agree that after seeing the Power-Glide beside the system you have assembled, it only looked LONG because there was nothing to compare it to and the diameter of all the components sent confusing signals (I try to lay a yardstick or a 8x8x16 cement block in the picture for a size reference.) I hope many of the Newbys who are reading "DIY" will learn that there many alternatives to the "Stock" transmission when doing a conversion. That is why I don't consider it "Preaching to the Choir" as Miziplix called it, I think of it as an "Evangelical Dissertation", Redundant to some of us. But, very enlightening, to others.


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