Calling Dave Kamp

Hi Joe!

Okay, so for the tractor... is it a NF or WF tractor?

If you're running a loader and it's NF, I would certainly recommend going to a WF setup, to improve safety and stability.

Next, if you want this thing to be a genuine worker, you're gonna need power steering in the front end. I don't recall if yours had any sort of power steering, but based on your question, I'm betting it don't... or if it does, it ain't workin'. A loaded bucket demands a strong axle and serious power steering in order to really work hard without killing the operator's arms.

Tell me more about what you got, and post some pictures of the setup.

Dave Joe is asking about his d14 industrial backhoe.   So yes it is a factory wide frontend with power steering.   The issue is with a ts500 loader that front end just don't turn good. I have the same problem with my d15 industrial.   I have not tested the pressure built by the power steering pump but like Joe I don't know what it should be.   From what my uncle saids about the d14 they bought new years ago mine is working normal or close to it but once you fill that bucket getting out of the barn is tricky....
As Joe said getting one of the power steering pumps rebuilt is crazy expensive.   That is why I suggested replacing the pump with a priority flow valve off the hydraulic pump running the loader. That would allow Joe to use the cheaper pump he has that works.

I have wondered if there is a safe way to increase the force turning the tires. My concern is of course that I don't want to put a bigger cylinder in only to break something else.

Edited by Dan73 - 09 Dec 2016 at 5:57am

can't Joe....he died, and that tractor is long gone somewhere

The old farmall wide front ends I have seen have a rod connecting the two tires and the wheel turns one tire the connecting rod turns the other tires maybe something like that could be made to work on the back side of the stock front end.

The tires will help. I mounted a pair of 265 tires off my pickup on the rims of my d15 helps alot with cutting in like you said. But even in my barn with wet cement cleaning it out it is hard to turn. I hit my poor 250 or so year old barn the other day and felt bad fixing the old post I knocked down.

Okay, let's start from the beginning:

Loaders present several interesting additional stresses on a tractor. First, is obvious- more weight on front tires, which causes more turning frinction... 'scrubbing'... This translates to increased load for turning. As others noted, if you're rolling, the turning load is greatly relieved, because you're actually only scrubbing 'part' of the tread contact surface as you turn the wheel.

Second, the tires, having more ground pressure, will sink in sooner, and deeper than they did with less pressure. How much? Depends on two factors... first... tire pressure. If you put 10psi in a tire with 10 square inches of ground contact, that's 100 pounds of support. Put 200 pounds of weight on the tire, it's gotta find another 100 square inches of support area. Take some eyeball measurements of your unladen tire's contact patch, and put a pressure gauge on the stem, do some pencil-scratching on paper to see where you are in REAL LIFE... and then get a big bucket of gravel lifted up, and repeat the process, you'll see what's happening in your application.

Next... steering geometry. If you ever wonder why your tires looked like they had a 'lean' outward at the top, you're gonna find out quick. One would think that a tire that's perfectly perpendicular to the ground would be the most sensible alignment, but that only works when a machine doesn't have to turn with grace. We take for granted that sars on the road get aligned by professional service techs per engineer's specifications and everything works like magic. The numbers they work with are based on a myriad of factors, along with terms like Ackerman Angle and Roll Center, Crown, Aspect Ratio, and stuff. Now let's skip the auto-tech and change to agricultural/heavy equipment mode, where there's some simpler considerations.

Look at the spindle. See the axis where the wheel pivots as it steers? The tire changes it's angle to steer there.

Imagine that tire, instead of being where it is, was about two feet out further from the tractor... out hangin' on a stick. Call the spindle's pivot the Kingpin (even if it's not). Now put a heavy load on the axle, where's the highest strain? Well, it's on the point where the spindle meets the kingpin... and of course, there's lots of strain on the kingpin, too. It's because the tire's contact point is WAY, WAY out from the pivot axis of the spindle... far from the kinpin's pivot point.

Let's say you were to drive that funky-spindled thing, and drop one tire into a hole, or bump into a tree. Where's the shock force of that bump go? Right through the steering rod. Why? Because there's a ton of leverage from that wheel hangin' out three furrows.

Move that wheel inward, so that it's contact point is really, really close to the kingpin axis, and all those funky forces go away.

(try to expain this to the punks who drive 'squash-bug cars with 'fart' mufflers... but don't hold your breath- you can't fix stoopid).

---Flip to pg217 in your Geometry textbooks, we'll revisit this later

Ever notice how some tractors, like the Allis B, C, CA, the Ford N, Case VAC... how they have steering boxes mounted to the chassis, and drag links that go forward to some pivot point near the axle, then another link goes to either one knuckle, or the tie rod between wheels?

If you have one of those tractors, jack up the belly, so the front axle is off the ground and able to wobble right left, free. Grab one wheel, and wiggle it, watch the steering wheel. Feel sloppy? Look at the linkage. There's slop between wheel and wheel bearing. Slop 'tween knuckle and axle, slop in the tie rod end. Slop in the drag link, pivot, and other tie rod, all the tie rod ends, steering box, and lastly, the wheel worm. Ever wonder why the old NF Farmall wanders down the road like a drunk with ADHD looking for a half-used cigarette? Start eliminating slop, one piece at a time... there's a ton of places for it to party.

But once you get it all tight, repeat the task... and when you do, take a ratchet strap and lock the steering wheel down so that it CANNOT turn. Swing the axle from full down on one side, to full up, and observe the tire angle. You'll notice that from full down, to full up, that the tires actually CHANGE ANGLE. That's because the steering linkage is not perfectly on the same axis as the axle pivot point... it's swinging around, and to accomodate the changing distance in that swing, the tie rod, etc., all has to move to compensate.

Also consider for a moment... you have a steering box pushing forward and aft... and it's pushing on a knuckle connected to the end of an axle. If there's slop in that axle pivot, not only are you trying to pivot a tire, you're pushing one side of the axle forward and back. Now drive down the road with little or no steering input, that axle's wandering fore and aft, and that changes the tire angle... you have what Jeep guys affectonately refer to as 'death wobble'.

It doesn't take too much thinking to realize that sloppy, erratic, unpredictable steering is something that makes accurate machinery operation very tiring and frustrating. Thing is, when your'e actually DOING it, you don't notice it- you just get angry and tired. Like having a cockleburr stuck in your waistband...

--- Back to knuckle geometry ---

IF you consider that the knuckle offset effort, along with the articulating (swinging) axle variation and all the slop encountered with a complex mechanical steering linkage, it's not hard to understand how rolling over a lump, or through a hole, with a common tractor could wind up whipping the steering wheel and busting your thumbs and fingers. Put another thousand pounds in a loader bucket that's a 500 pounds, hanging out 48" past the front of your front tires, and a ton of counterweight on the back, and tell me how important it is to have good steering on a tractor.

--- Open your service manual for your favorite WF tractor... look at the axle ---

If you wanted to make the steering on your tractor the least sloppy, and the least reactive to holes in the ground, and the least reactive to axle articulation, you'd do everything you could to keep the reaction loads simple. There's a reason why the steering of a Model A Ford is no longer popular... we have rack-and-pinion... and although it seems a whole lot more complex, the geometry and reaction loads are a whole lot SIMPLER. No Bump Steer.

Fat tires will keep ground pressure low, and Fat tires reduce sinking in deep, which in many cases, means the tire is stuck in a crack that NO steering force within reasonable planetary loads will overcome. Unfortunately fat tires frequenly come at the expense of wheel offset- farther from the pivot axis. IF you have a rim/tire combination that gives you twice the tire surface, without moving the rolling centerline any farther away (or better yet, moves it CLOSER to the axis of the kingpin), then you're golden).

Next, remove the steering linkage mess. Remove the axle's pivot axis from all the steering problems. The two front wheels are connected together with a tie rod. Put two hydraulic cylinders up there. One end of each on the axle, other end on each knuckle. Steering forces are now 'isolated' to being between the axle and the knuckle, no where else. Front axle pivot sloppy? No big deal.

---A Reading The Second chapter of the book of Farmall: ---

Do tractor manufacturers do this? Not often. Why? Because it usually complicates having front axle adjustability.

The other thing tractor manufacturers don't do, is build front axles that are beastly strong with respect to supporting intense axle pivot loads, or span loads for the front axle. Why? Because it's a farm tractor, not a forklift truck. It's gotta be adjustable, and it's gotta clear crops, so having a beastly front axle isn't directly compatible with it's intended purpose.

You can try a vareity of 'fixes' to improve the steering and durability of a stock axle, but IF you really, really, REALLY want it right, sit down with a piece of pizza, a beverage, and a pad of paper and pencil, and start scratching out drawings..

Next up... Power steering, in a nutshell... or a nuthouse...

Model A steering box I believe is a worm gear. My dad built a garden tractor using one along with lots of other model A parts and I don't remember it kicking when hitting things. Now the Model T steering is by spur gears and kicks a lot. Also the 9N and 2N tractor steering boxes were bevel gears and kicked hard. The 8N went to a ball worm and cured that kick. I'll check that model A steering box next time I'm at the farm, if I remember it.

Gerald J.

A hydraulic system of the simplest type, consists of three components:

An input, which is typically a pump, but could be a piston in a cylinder...

Plumbing, to connect it to a load...

An output, which could be a cylinder, a motor... or anything else someone dreams up.


A more complex system will have a pump, a reservoir, some filters, a valve or two, some plumbing, and several cylinders, motors, etc.,

But here's the basic property of a hydraulic system:

Pressure of a fluid, has the abilty to generate force.

IF you move a VOLUME of fluid, that force can be continued over a DISTANCE.

From 5th grade science, in SIMPLE MACHINES, you learned that Work is the result of applying force, over a distance.

Work = Force * Distance.

Let's say you lift a 10lb load 10 feet. that's 10 x 10 or 100 foot-pounds That's a fair amount of work, right? Now, work can be done in a second, or a minute, or an hour, day, month, year, or eon.

I'm gonna pick on Joe. Let's Joe takes a day out of his busy schedule to lift that 100 foot-pound load. I'm not being mean here... Joe's put in his fair share of time supervising the back end of a shovel, he's no spring chicken... needs to take it easy on his back, okay?

But my daughter is a soccer goalie... she's young, energetic, and quick, and she's strong for being 12 years old. She will take ten minutes to do it, because she'll do it a half-pound at a time, tossing 'em up underhand.

I'm gonna do it in four seconds,'cause I can flip that 10-pound box up there with one hand.

I've got a small-block chevy sitting on the floor, with a belt on it's crankshaft, and I can set that 10 pound box on the belt, and it'll chuck it up there in a fraction of a second...

What JOE does in a day, my daughter can do a hundred or more times. I can do it several thousand, but that small block chevy can throw THOUSANDS upon Thousands up there in the timespan that anyone else would get just a few.


What's the difference?

Power.   Power is force x distance X TIME.

Since I can do it faster, I can do it MORE than my daughter, and more than you. The engine has even more on tap. Easy, eh?

Now 'm gonna throw in one more thing: Duty Cycle.

Joe can sip coffee, read the newspaper, and do one a day, and if he lived a million years, doing that 100 foot pound lift once a day, every day would likely not even be enough to keep him in shape.

My daughter would be perfectly fine with flinging them for six hours, but I'd have to take her out for ice-cream when we were done.

I'd probably be able to do several days of sixteen hour shifts, with a water break every few, of course.

The 350 chevy would blast us all off the planet, but did I mention that there's no cooling system on that engine? Yeah, it'll throw a mess'a boxes, but eventually, it's gonna overheat and seize... so either I shut it down to cool for two hours between 15 minute sessions, or it turns into liquid metal. (remember... liquid metal?)

This is what we call DUTY CYCLE. How long a device can operate at a given POWER LEVEL, without having to COOL DOWN.

When something is rated for 100% duty cycle, that means it is designed and INTENDED to survive at that power level, WITHOUT STOPPING... EVER.
Now, I'm a hard-a$$ when it comes to designing things. I like things built to 200%... I like 'em to be able to run continuous duty, in a state of OVERLOAD... forever.

Call me crazy, and your're probably right, but I don't like stuff that breaks... and I don't like stuff that overheats, falls apart, or wears out fast. Power, is the ability to push a certain amount of force, a certain distance, in a certain time. Duty cycle, is how long something can develop that power, before it needs to rest. Doing little improvements, like taking a bull-whip to Joe's back, might increase his productivity. Bringing my daughter ice-cream and offering her a pair of goalie gloves and a new kitten would step up her game. Offering me shares in a fast-growing major company would get my attention, and the small-block chevy would benefit greatly from the addition of a good cooling system. EACH one of these will have a positive improvement on productivity, and SURVIVAL.

Survival is important... and there's two terms I"ll mention here, because they're related:

Mean Time Between Failure... aka "MBTF". That's how long something can be expected to run under expected service ratings, before it's gonna die.

Mean Time Between Overhaul... MTBO... how long it'll run under expected conditions, before it wears to the point that it needs an overhaul to continue at it's original design performance standards.

So when you're thinkin' design, keep in mind:

Work= Force*Distance
Power = Work * Time
Duty Cycle = Percentage of survivable operation at a given power level.
MBTO = how long 'till you'll need to rebuild
MBDR = how long 'till it's junk.

Shall we get back to hydraulics? Sharpen your pencils, and bring calculator to class...

Edited by DaveKamp - 09 Dec 2016 at 8:32pm

So on to Pumps.

As I noted, Hydraulic pumps come in different flavors... fixed, variable, and hydrostatic.

Fixed displacement pumps are like gear pumps, and piston pumps. When the gear pump makes one full revolution, a fixed (known, and constant) amount of flow MUST OCCUR. I say MUST, because if it's a one cubic-inch-per-revolution pump, and you only allow a half-cubic-inch, it will NOT make the full revolution... Well... if you put enough force on the shaft, it will, but what's left of your pump will be small pieces. The basic rule is, that the PUMP MUST HAVE someplace to flow oil to. If you 'stall' the pump, either you'll stop the prime mover (engine or electric motor), or a component will rupture, a seal will blow out, or the pump will become a grenade. Let's not do that, okay?

With a fixed displacement pump, we make sure it stays happy by always PROVIDING a pathway for oil to flow. First, is by having an OPEN RETURN PATH... or as they call it, and 'open center' system. An open center system, is a valve system where fluid from the pump goes to the valve, and if no valve is being used, the fluid is returned totally to the tank (and frequently, it's sent that way through a 'return filter', for the purpose of catching any debris that may have found it's way that far). Hydraulic valves must be 'made' to be 'open center', to provide this return path function.

Likewise, if you pull a handle to extend a cylinder, and that cylinder reaches it's endpoint, there MUST be some place for the pump's oil to flow, otherwise the engine will stall, line will burst, cylinder seals blow out, or pump -> grenade... Capiche? The standard technique, is for a Tee fitting to be installed into the pump's output line somewhere, and a PRESSURE RELIEF VALVE installed into the tee in such a way that any fluid pressure in excess of the PRV's setpoint, will be diverted back to the TANK. One important note, is that the PRV has TWO very important characteristics... the first is pressure relief setpoint, and the second is FLOW VOLUME.

A fixed-volume pump moves a certain amount of flow for each revolution. If it's a 2.31 cubic inch pump, and you turn it at 100 RPM, that's 231 cubic inches (one gallon!) per minute. Turn that pump at 1000rpm, and that's 10 gallons a minute. 2000 is 20gpm.

Let's say you have a pump that by virtue of it's displacement, and the engine's running speed, grants 10gpm at 1000rpm... so you put a pressure relief valve set for 2500psi at 10gpm in it's output line, and downstream is an open-center valve. You start the engine, and bring it up to 1000rpm... all the pumps' flow will go out to the valve, and (because it's open to return) all flow comes back to the reservoir... no problems. Pull on a valve handle, extend a cylinder to full length, and when it hits it's endpoint, it stops. Consider for a moment that the cylinder's RESISTANCE to extension doesn't change the SPEED at which it extends or retracts, but if there's no resistance, the pressure in the hydraulic lines will be essentially NOTHING. If that cylinder was pushing a wedge through a piece of soft maple, then line pressure would rise until the cylinder managed to push the wedge INTO the wood, at which point, the amount of pressure in the line would drop to nothing more than what was required to push the wedge through the split log. The cylinder will extend at whatever RATE has been determined by the cylinder's volume, and the pump's volume, and the pump's input shaft speed.

Let's say you speed up the engine, to make the ram move faster... but you don't change the VOLUME RATING of the valves, lines, and pressure relief...

...and you allow the cylinder to reach it's end, and keep holding the valve... you're stalling the pump. Pressure in the line skyrockets, but the pressure relief valve bangs open, and diverts all flow back to the tank.

Unfortunately, while you had a 10gpm safety valve, you're spinning the engine and pump at a speed HIGHER than the prior pump calculations assumed. Your 10gpm pumping plan is now 20gpm, but your SAFETY VALVE will be forced to flow TWICE the amount of fluid that it was originally designed for. This is a recipie for disaster... so do your pump volume calculations very carefully, and when it comes to return lines, return filters, and check valves, OVERSIZE THEM.

   Mr. Professor,,,(holding up hand and jumpin up and down)
   Mr. Professor,,,you have just made me realize my thought of using an automotive PS pump was impulsive to say the least, as it being a vane type apparattus,, would not have worked in this application. The pump in the D14 is a "fixed Displacement" or as we Crude oil Boilers used to say a " Positive displacement" pump. But you have made me curious to look INSIDE the current system for a possible fix or upgrade,,,,,
   When you compare the physical size difference of the PS pump to the size of the front mounted hydraulic pump (FMP) ,,,,the FMP is maybe at least 2 1/2 times as big as the PS pump cause the FMP has to fill considerably more cylinder areas and prolly at close to the same pressures as the PS pump,,right?
  The factory PS pump has 2 very small gears which make it a Fixed or positive displacement pump. I never thought to count the teeth on the drive gear on the engine, or the driven gear on the pump to see what it's RPM might be but do remember the drive gear was about a 3-1 ratio. HMmmm,,,I better see bout puttin a pressure gauge on the discharge of the PS pump,,,cause you gonna want to know on the test,,,,,

Back in the fraction days we thought 22/7 was a pretty good value for Pi.

When doing calculations of earth surface distances, a three digit value for Pi is plenty good,  this ball isn't that precisely made. Even at sea level the equator is longer than a loop over the poles. And because it hadn't been surveyed before the meter standard was established, the meter was defined as 1 ten millionth of the distance from the equator to the north pole. It isn't exactly.

As for pressure, over the century, hydraulic parts have been made for several different pressures, typically 1250, 2000, 2500 , and 3100 psi. And those pressure ratings have to apply to EVERY part in the system. A 1250 PSI hose on a 3100 psi system is going to split. A 3100 psi cylinder on a 2000 psi system won't break, but will give only the force from 2000 psi and probably will have a larger piston rod so will be weaker on retract force than a 2000 psi cylinder. It will also be heavier and cost more. The highest pressure I know of for ag equipment is 3100 psi in later Allis tractors. I'm sure higher pressures have been used in construction and industrial equipment.

I have seen ordinary water pipe fittings used on tractor and implement hydraulic plumbing. That is not a good idea. Those fittings are only rated at 125 psi and I have seen a couple split with less pressure, one carrying natural gas burned an apartment building in Fort Dodge, one at ISU carrying water to fire protection nozzles soaked a new laboratory. 2000 plus pipe thread parts are made and sold. Baum Hydraulics is a good source for all things hydraulic and lots of mechanical stuff like bearings and hardware. http://www.baumhydraulics.com Their catalog in .pdf format searches better than their web site. The catalog shows suggested resell prices, there is a discount, usually hidden next to the word DATE. DATE 2000 means 20% discount for that page.

Gerald J.

Oh man. Wished I could absorb and retain everything said above. I know that even 10 years ago, I'd been studying and contributing, but anxiety, or old age, or stress from lack of income in my farming operation, or all of the above has shot my studying habits all to he!!. You guys are amazing.
   And Joe, I really am impressed with the two pieces of Allis Chalmers history that you have rejuvenated, and look forward to seeing them sometime. I hope that the D15 LP that you did is still in close enough proximity of you so that if'n I do get down to your neck of the woods sometime, we can go have a peek at it, too. And I hope you'll let me dig a hole with that back hoe. Darrel

Dan.....gits you a rear mount hay grapple, I have one and it works great! I can even puts big rounds up on a semi with mine. 

desertjoe wrote: Mr. Professor,,,you have just made me realize my thought of using an automotive PS pump was impulsive to say the least, as it being a vane type apparattus,, would not have worked in this application. The pump in the D14 is a "fixed Displacement" ...But you have made me curious to look INSIDE the current system for a possible fix or upgrade...    When you compare the physical size difference ...the FMP is maybe at least 2 1/2 times as big as the PS pump cause the FMP has to fill considerably more cylinder areas and prolly at close to the same pressures as the PS pump,,right?

The long answer, is No.    

Okay, so in comparison to the PS pump, the front pump is physically twice the size and more... yes, it's a fair assumption that the volume required for operation of the loader lift and curl is higher than that of the power steering... but realize that a positive displacement pump's volume is directly proportional to it's operating speed... so make sure you consider all of the pumps' drive ratios prior to jumping to conclusions. If the PS pump is driven off the timing gear, for instance... it may be more like 1/5th of the volume, because it's turning at half crankshaft speed.

desertjoe wrote: ...The factory PS pump has 2 very small gears which make it a Fixed or positive displacement pump. I never thought to count the teeth on the drive gear on the engine, or the driven gear on the pump to see what it's RPM might be but do remember the drive gear was about a 3-1 ratio.

Yep, that has a very definite impact on how much the pump will flow.

desertjoe wrote: ...I better see bout puttin a pressure gauge on the discharge of the PS pump, cause you gonna want to know on the test..

Here's where the gotchas make life fun... as the pressure you're gonna read will usually be just a smidgen on the high side of ZERO. Remember, if it's a fixed displacement pump, and you're not putting any load on a hydraulic circuit, the VALVE will return ALL hydraulic fluid back to the tank, with basically no restriction, so your pressure gauge is gonna read... Nothing. That engine could be screaming... and there'd be fluid flowing around in a circle through that valve like crazy, and there'll still be NO substantial pressure.

Why? Because it's doing NO HYDRAULIC WORK. When you start turning the wheel, the valve directs fluid into the steering assist ram... but if the steering presents NO considerable load (let's say you've got the front axle up in the air, cause 'you've planted the bucket deep), then it will require essentially NO force to make the wheels turn, so your indicated pressure will be dirty wool socks at best.

You won't see output PRESSURE readings worth squat, until you have a steering load which the system cannot overcome... like... a wheel buried in a narrow trench, and you're steering it to try to get it out, but it won't move. That's a classic case of a 'stalled' hydraulic ram... you're asking it to push against something that it cannot move. When you stall the cylinder, but keep trying to push it with the valve, one of three things will happen... you'll kill the engine, exceed the setpoint of the pressure relif valve, or something will swan-dive into the scrap pile.

   Hey Dave,,I been dwelling on one part of the factory D14 power steering system (PSS). On the D15 II I had, I had to remove and completely disassemble the whole front support due to a small oil leak at the steering shaft seal and one at the control valve body assembly to the front support.
  Now, I'm going on memory here,,,but the " Ram Cylinder assy" had a "gear rack" with slotted teeth, and you had to add/remove shims to the cover plate to tighten up the slack of the rack,,,,,I  have been been lookin at the internals of the PSS and I cannot remember what the purpose of the "cylinder ram",,,cause I can't figure WHAT the rack actually moves. The steering wheel shaft is the "input" to the PSS control valve, then the control valve,  thru a bevel gear drives the steering gear, which drives the vertical steering shaft, which turns the wheels.  All the above is on the left hand side of the huge front support but the cylinder ram is on the extreme right side of same,,,,?? I know it serves a purpose but memory has failed me on what it's job is on this one,,,,
   After re-reading your recent post,,,are you mayhaps, alluding to the possibility of a big chunk of the pressureized oil may be by-passing the control valve or the PRV on the pump itself thru it's pressure relief valve (PRV),?? It SURE could be a possibility,,,cause when I had the D14 pump apart on the 7th time, I noticed the check ball on the PRV port had a "groove" on the lower part of the ball,,,,almost like it had been machined like that,,and since I had never seen a PRV check ball like that,,,I assumed the ball had been replaced before and maybe a ball of lessor quality steel been installed and just wore the groove from the constant open and close on the seat.,,???
 I was talkin to a Farmer friend yesterday and he tells me he has "retrofitted" some of his loaders with a "Char-lynn steering assist" off some of his older combines and solved his problems with hard steering on those loaders,,,,!!! He said he left the original power steering systems in place, just added the steering assist on the steering shaft. ???