Bulldozer- weak axle

Mr. T. Minnesota · Jan 26, 2013

BD,
Enjoyed your explanation of the weak axle used with N tractors. Have a novice question- you stated the static capacity on an N tractor axle is 420 pounds. Is that 420 pounds per axle/hub or total capacity for the N tractor's front end? Reason for the question is if you load a trailer with a 1000 pounds, is it 1000 pounds per axle/hub or 500 pounds per axle/hub? Just curious!

Mr. T. Minnesota

Bulldozer · Jan 26, 2013

The estimated ~420# is the extra vertical static load applied at the hole in the axle through the king pin and bushing load path that the N series tractor could safely handle from accessories, etc.

The weight of the tire, wheel, splindle and any extra wheel weights do not contribute any gravity load to the center axle.

Since the axle is cast steel the material inherently has casting flaws (voids), which reduces the strength of the material compared to the same material being hot rolled, cold rolled or forged. However, the chances of the casting having a flaw in the region of maximum stress is rather remote ,but the allowable working load would be determined based on the void occuring in the worst possible spot, unless x-rayed.

ZANE · Jan 27, 2013

These tractors were made to pull a plow not tote a 1000 pounds or more on the front axle.

Zane

TheOldHokie · Jan 27, 2013

(quoted from post at 22:40:18 01/26/13) The estimated ~420# is the extra vertical static load applied at the hole in the axle through the king pin and bushing load path that the N series tractor could safely handle from accessories, etc.

The weight of the tire, wheel, splindle and any extra wheel weights do not contribute any gravity load to the center axle.

Since the axle is cast steel the material inherently has casting flaws (voids), which reduces the strength of the material compared to the same material being hot rolled, cold rolled or forged. However, the chances of the casting having a flaw in the region of maximum stress is rather remote ,but the allowable working load would be determined based on the void occuring in the worst possible spot, unless x-rayed.

I am no fan of loaders on N-series tractors BUT it seems odd that the factory engineers missed something that fundamental when they designed the Ford Industrial loader with a payload capacity of 1000#. Ford provided factory mounting kits for the 8N as well as the NAA, and Hundred series tractors mentioned in this brochure and all of those tractors used basically the same cast center axle. I guess this guy has no idea the danger he is in....

TOH

[u:1b2404143b][/u:1b2404143b][color=red:1b2404143b][/color:1b2404143b]

Bulldozer · Jan 28, 2013

Good work TOH.

Found three N series front end loaders on ebay.
One is a "Dearborn Farm Equipment" label loader, mounted on the tractor.
Another appears to be a home brew design mounted on the tractor
The third is a basket case & removed from the tractor.

The two tractor mounted loaders appear to be attached to the front axle support weldment allowing rotational movement of the front axle about the king pin.
This design places the king pin and center axle hole in the load path to ground, placing load on the weakest spot on the center axle.

However, the Ford industrial loader you posted appears to be attached to the front knee, which is cast steel. Noticed there are two holes on the knee extension adjacent to the vertical cylinder that houses the forged spindle.

These holes are not used to attach the center axle to the knee extension.
Believe this to be the attachement point for the Ford "industrial" loader. This attachment point takes the center axle out of the load path to ground. This attachment point would be much prefered over using the center weldment support,
as was used on the Dear farm equipment design.
However, using the knee extension holes to attach the loader frame would fix the center axle and prevent it from rotation.

Found a 1959 sales brochure for a Ford 703 loader design for a NAA, 8N , Oliver, 55 MF tractor with a 1300# load capacity.
The brochure is titled" Ford extra heavy duty loader series 703".

This loader also appears to be attached to the knee extension rather than the center support.

After many years of farm work fatigue cracks could develop in the axle sand casting or knee extension sand castings, even if there were no initial flaws in the castings. My 8N spent 60 years plowing corn fields in Merced, CA.

Before straping on a loader to N series, would have the center axle and knee extension parts checked for cracks, especially for the center support mounted type for safety.

After checking the center axle and knee extension for cracks could increase the allowable working load on the center support from 400# to 800# and believe N series would safely handle a 1000# payload on the Dearborn Farm Equipment type loader, since a portion of the pay load and loader frame weight is shared by the rear axle.

For comparison found some loader ratings on current tractors of similiar HP to the N series.

NH T1500, 30 HP: 875# load capacity
JD 1 series,22-25 HP: 825# load capacity
JD 2000 series, 24-30 HP: 1023# capacity
JD 3000 series 23-30 HP: 1186# capacity

These tractors all have support frames for the engine rather than a "stressed engine design" like the N series..
All have fixed front axles that do not rotate compared the N series.
The loaders are attached to the fabricated tractor frame with no sand cast parts.

TheOldHokie · Jan 28, 2013

(quoted from post at 10:45:51 01/28/13) Good work TOH.

Found three N series front end loaders on ebay.
One is a "Dearborn Farm Equipment" label loader, mounted on the tractor.
Another appears to be a home brew design mounted on the tractor
The third is a basket case & removed from the tractor.

The two tractor mounted loaders appear to be attached to the front axle support weldment allowing rotational movement of the front axle about the king pin.
This design places the king pin and center axle hole in the load path to ground, placing load on the weakest spot on the center axle.

However, the Ford industrial loader you posted appears to be attached to the front knee, which is cast steel. Noticed there are two holes on the knee extension adjacent to the vertical cylinder that houses the forged spindle.

These holes are not used to attach the center axle to the knee extension.
Believe this to be the attachement point for the Ford "industrial" loader. This attachment point takes the center axle out of the load path to ground. This attachment point would be much prefered over using the center weldment support,
as was used on the Dear farm equipment design.
However, using the knee extension holes to attach the loader frame would fix the center axle and prevent it from rotation.

Found a 1959 sales brochure for a Ford 703 loader design for a NAA, 8N , Oliver, 55 MF tractor with a 1300# load capacity.
The brochure is titled" Ford extra heavy duty loader series 703".

This loader also appears to be attached to the knee extension rather than the center support.

After many years of farm work fatigue cracks could develop in the axle sand casting or knee extension sand castings, even if there were no initial flaws in the castings. My 8N spent 60 years plowing corn fields in Merced, CA.

Before straping on a loader to N series, would have the center axle and knee extension parts checked for cracks, especially for the center support mounted type for safety.

After checking the center axle and knee extension for cracks could increase the allowable working load on the center support from 400# to 800# and believe N series would safely handle a 1000# payload on the Dearborn Farm Equipment type loader, since a portion of the pay load and loader frame weight is shared by the rear axle.

For comparison found some loader ratings on current tractors of similiar HP to the N series.

NH T1500, 30 HP: 875# load capacity
JD 1 series,22-25 HP: 825# load capacity
JD 2000 series, 24-30 HP: 1023# capacity
JD 3000 series 23-30 HP: 1186# capacity

These tractors all have support frames for the engine rather than a "stressed engine design" like the N series..
All have fixed front axles that do not rotate compared the N series.
The loaders are attached to the fabricated tractor frame with no sand cast parts.

Nope. All model variants of the Ford Industrial loader attached to the front axle bolster just like the older Dearborn loaders. Item #2 in the Ford parts diagram shown below is the attaching bracket used on the 8N and item #3 is the attaching bracket used on the NAA and Hundred series. All of the front end load from the Industrial loader is carried by the center hole in the front axle on all of those machines and that is way, way more than 400# regardless of the improved lift geometry. Broken spot welds and hogged pivot holes on the bolster assembly from the added loads are a very common failure with all of these loaders but I have never heard of a fractured axle caused by any loader.

On all of these tractors the axle pivots in the center and that pivot point is the load path for any load that isn't attached directly to the front axle, axle extensions, or wheels. Since the axle and it's extensions pivot up and down with the terrain they are a very poor attachment point for a loader. The only loader I have ever seen that attached to the axle or it's extensions on any Ford tractor are the old N-series Sauder loaders which flopped around with the axles and were darn near unusable. Aside from their quick attach feature they were an absolutely horrible design.

TOH

Bulldozer · Jan 31, 2013

Have reseached this front loader attachment thing some more.

Found the sales brochure for the Ford Industrial Step-On loader you previously posted.
Believe is the same as the Ford extra heavy duty series 703 loader.

Also the brackets shown in your last post are hydraulic pump attachment brackets for thr FORD 68 standard loader, Ford heavy duty loader and Ford 79 standard loader and not the loader frame front attachment bracket.
The graphic appears to be is taken from the Supplement No 3, master parts books.
This parts book show two 1" bolts in Figure 4 for attaching loader fram to bracket.
However, the bracket shown in figure 6 does not appear to interface with an N series, maybe a 600 series.

I agree with you on the location of the loader frame front support for all of the Ford Dearborn front end loaders where the attachment is to a replacement king pin or to the axle center support weldment.

It appears that on the Ford 19-8A or 19-22 the original king pin is replaced with another king pin with a steel plate welded to the king pin. The king pin plate has two holes that interface with a steel plate welded to the loader frame.

Maybe other Ford loaders manufactured for N series has this type of front attachment design.

However , found the parts manual for the
Ford 19-7 ,where front attachment appears to interface with four bolt holes on the axle center support engine pan holes. There are two bracket plates, one each side of the center support.

A free body diagram of the loader support frame indicates a force is applied at the
axle hole ~ 2800# ,based on 1000# payload and bucket weight at lowest position. The greatest load is applied to the from axle in the lowest bucket position.

Need to firm up some geometry to better converge on this applied axle force at the center.

I know there is low probability for castropic failure of the cast axle part, but it would not get an FAA certification for flight.
It's a tractor.

Still do not understand the rotation feature front axle.
Seems like for a front end loader it would more desirable for the front axle to be fixed.

All the NH & JD utility tractor brochures show a front end loader on the cover. This still must be the hot ticker demand for utility tractors.

TheOldHokie · Jan 31, 2013

(quoted from post at 13:38:26 01/31/13) Have reseached this front loader attachment thing some more.

Found the sales brochure for the Ford Industrial Step-On loader you previously posted.
Believe is the same as the Ford extra heavy duty series 703 loader.

Also the brackets shown in your last post are hydraulic pump attachment brackets for thr FORD 68 standard loader, Ford heavy duty loader and Ford 79 standard loader and not the loader frame front attachment bracket.
The graphic appears to be is taken from the Supplement No 3, master parts books.
This parts book show two 1" bolts in Figure 4 for attaching loader fram to bracket.
However, the bracket shown in figure 6 does not appear to interface with an N series, maybe a 600 series.

I agree with you on the location of the loader frame front support for all of the Ford Dearborn front end loaders where the attachment is to a replacement king pin or to the axle center support weldment.

It appears that on the Ford 19-8A or 19-22 the original king pin is replaced with another king pin with a steel plate welded to the king pin. The king pin plate has two holes that interface with a steel plate welded to the loader frame.

Maybe other Ford loaders manufactured for N series has this type of front attachment design.

However , found the parts manual for the
Ford 19-7 ,where front attachment appears to interface with four bolt holes on the axle center support engine pan holes. There are two bracket plates, one each side of the center support.

A free body diagram of the loader support frame indicates a force is applied at the
axle hole ~ 2800# ,based on 1000# payload and bucket weight at lowest position. The greatest load is applied to the from axle in the lowest bucket position.

Need to firm up some geometry to better converge on this applied axle force at the center.

I know there is low probability for castropic failure of the cast axle part, but it would not get an FAA certification for flight.
It's a tractor.

Still do not understand the rotation feature front axle.
Seems like for a front end loader it would more desirable for the front axle to be fixed.

All the NH & JD utility tractor brochures show a front end loader on the cover. This still must be the hot ticker demand for utility tractors.

Look - you can argue all you want but I build and sell reproductions of these brackets and I have studied them to death. They all attach to the bolster in one way or another and the brackets in that parts diagram are the front hanger for all of the variously numbered variants of the Ford industrial loaders. The loader has two large pins in the subframe that fit into the large reinforced holes on the bottom outside corners of that front hanger. The 8N version of that hanger also had struts that attach to the bottom of the bolster to further stiffen the hanger.

There have been a multitude of variations on this central design and some versions mount the pump to the hanger - others mount the pump on the loader frame. But the bolster bracket always acts as the front hanger for the loader and all of that weight is carried by the axle center section. It never gets airborne and it handles the additional load fine.

Off the top of my head I can't think of of any model rubber tired agricultural tractor that has a fixed front axle.

The picture below is one of my reproductions of the Dearborn (aka Ford) designed hanger for the 19-8 loader used on the Ford 9N. It is the design that is the basis for all of the later variants.

TOH

Bulldozer · Jan 31, 2013

Yes, the unpainted plate, welded to the replacement king pin seems to be the design for the Dearborn N series front end loaders.

Have found Dearborn parts manuals where this replacement king pin/plate weldment was bolted to the loader frame.

Have seen this same plate/king pin in operating manuals with 9N riveted center support and the 8N welment center support.

Have studied many archives where a guy bought a Dearborn loader and could not figure out to attach it to the front. Nothing fit. Believe they finally realized the original king pin would have to removed.

If you look at the design of the NH 1500 utility tractor, JD utility series 1000,2000,3000 all have fixed front axles to the frame.

TheOldHokie · Feb 1, 2013

(quoted from post at 01:53:21 02/01/13) Yes, the unpainted plate, welded to the replacement king pin seems to be the design for the Dearborn N series front end loaders.

Have found Dearborn parts manuals where this replacement king pin/plate weldment was bolted to the loader frame.

Have seen this same plate/king pin in operating manuals with 9N riveted center support and the 8N welment center support.

Have studied many archives where a guy bought a Dearborn loader and could not figure out to attach it to the front. Nothing fit. Believe they finally realized the original king pin would have to removed.

If you look at the design of the NH 1500 utility tractor, JD utility series 1000,2000,3000 all have fixed front axles to the frame.

From the JD 3000 sales brochure:

[b:f17d513a37]FRONT/REAR AXLE:
Center Pivot Front Axle
Spur Gear Final Drives[/b:f17d513a37]

I know nothing about this JD 3005 tractor other than what was in that brochure and what I can see in this picture. But I'm going to go out on what I think is a pretty solid limb and bet the differential housing on that front axle is mounted to a pivot pin in the center of that box frame just like the front drive axle on my remarkably similar looking Kubota 4WD. If you look closely you can see the pivot pin at the top of the differential housing and the travel limiting stops on the top of the axle housing and underside of the frame. I suspect you will find the other models you mentioned all use a very similar if not identical setup.

TOH

PS> Just to make it a little clearer I added this parts diagram showing the pivot pin receiver which appears to be an integral part of the front axle/differential casting.

JMOR · Feb 1, 2013

(quoted from post at 01:53:21 02/01/13) Yes, the unpainted plate, welded to the replacement king pin seems to be the design for the Dearborn N series front end loaders.

Have found Dearborn parts manuals where this replacement king pin/plate weldment was bolted to the loader frame.

Have seen this same plate/king pin in operating manuals with 9N riveted center support and the 8N welment center support.

Have studied many archives where a guy bought a Dearborn loader and could not figure out to attach it to the front. Nothing fit. Believe they finally realized the original king pin would have to removed.

If you look at the design of the NH 1500 utility tractor, JD utility series 1000,2000,3000 all have fixed front axles to the frame.

" ...have fixed front axles to the frame." This, I must say, seems beyond any realm of belief or reason-ability. Consider that tractors common-ally operate on uneven terrain. Further consider on front wheel dropping in a hole/low spot with a full bucket load. Now you have a tractor with one rear wheel in the air. Tractor now stuck. I don't believe any such " ...have fixed front axles to the frame." designs are out there.

Bulldozer · Feb 2, 2013

Ok, you win, the front axle is not fixed to the frame, but has a center pivot on JD & NH utility tractors

Stand corrected!

Looked up the exploded parts view of the JD 3005
compact utility tractor on the JD website.
This tractor is about as close to the N series as anything on the market, accept for maybe the NH 1500 compact tractor.

The 4WD model has the center pivot housing integal with the differential housing. Appears to be a very heavy duty casting.

The 2WD model has a front axle with a center pivot with a configuration of very similar geometry to the N series, except it is a weldment rather than a casting.

Also looked up the exploded parts view of the NH 1500 compact tractor

The 2WD & 4WD models both have a front axle center support. The 4WD model pivot has zero offset to the front axle. Again the 2WD model front axle geometry is similar to the N series
It is a weldment rather than a casting.

Anonymous-0 · Feb 2, 2013

Tip: next time dozer, you won't need to cave or apologize, if you stick to speaking to only subjects that you know something about & have real hands on experience with, rather than speculation, hearsay, what saw on Internet, etc. HTH

P.S. this applies to other topics that I have seen you "blow hard" on, as well.

Bulldozer · Feb 5, 2013

Still working on the front axle.

Now have a good handle on the maximum stress based on an sales brocedure 1000# payload based on good geometry and weight data.

Have searched the archives and other sources to find the exact alloy for the front axle.

No luck.

Do not want to assume plane wrap A36 structural steel with a yield strength of only 36 ksi.

If you guys ever take a airplane ride on a Boeing 787 or Airbus A350 Im the guy who performed the stress analysis and FAA stress report for flight certification on the flight control actuators. Spend 40 years doing structural & thermal stress calculations.

The only way to find the strength of the front axle is to run the numbers.

Anonymous-0 · Feb 5, 2013

Looked over thread. Must assume that things must be real slow for you being out of a job and all. Analyzing a 60 year old design that has more than proven itself by now is a great waste of time that might be better spent re-analyzing the now grounded 787 Dreamliner.

Bulldozer · Feb 5, 2013

Totally retired now..lots of time on my hands.
That electro mechanical flght control actuator must have fryed the batteries on the 787 and grounded it.

Bulldozer- weak axle

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