New Holland (Prince) Loader Valve Will Not Stay In the Float Detent Position

[toot77]

I have a 2010 New Holland T1520 with the 110TL loader. The OE loader valve is a Prince valve. My problem is that the valve will not stay in the float detent position when using my front snowblower. I have owned this tractor for the past 2 years.

I also have a 1995 New Holland 1520 (which is what I have used the snowblower for the previous 27, or so, years. The OE loader valve on the 1520 is a KYB Kayaba valve. While it has worked fine, i.e. usually stays in float, I do have a 1993 service bulletin for the Kayaba valve that my dealer gave me in 1997 that describes adding a 0.075” shim to the detent spring to improve keeping the valve in float detent by adding 8 lbs force to it. I must have questioned it once way back. I do not recall if I made the service bulletin mod.

My question is; is there a comparable mod that can be made to the Prince valve to make it stay in float detent? The Prince's detent does not look like the Kayaba service bulletin diagram.

The prince valve casting number looks to be C-689 Rev G, but is hard to read.

 

[Harry in Ky]

I think if you have the pertinent information on the valve, you should try to contact Prince with your question. Maybe through a Prince dealer or distributor if all else fails. While you may well get some responses here, I rather doubt any will be all that helpful. Maybe I'll be surprised.

 

[rScotty]

If you post a photo of the valve assembly we should be able to identify the float detent part of your FEL valve set. Take several views.
The float detent "latch" is pretty obvious on most FEL valves and is essentially a rod-like extension on the far end of the loader arm valve spool. That extension lives in a metal cannister where it ngages a trapped ball and spring detent mechanism.

If yours is the simple type, it is routine maintenance to clean the dirt and rust out.

In most valves, that float detent assembly enclosed in that cannister that has a weep hole at the end. That weep hole is the problem because it can also let water and dirt into the cannister. The right cure is to take the cannister off, clean and polish the rod, detent ball or cam face, and check that the spring is still good. As you found, some can be shimmed - but clean it first.

The "set of pants cure" is to squirt some WD-40 into that weep hole and see if that helps.....

First things first- get some photos so we can confirm.
luck,
rScotty

 

[toot77]

Here are some photos of the valve.

The New Holland part number is 86535713. From other older posts here, and from Prince info online, it appears that the closest stock Prince valve might be a LVTR series valve. A Skematic from New Holland parts shows the cross section of the valve.

The float detent looks different from the Kayaba valve. On the Kayaba valve, according to the old New Holland service bulletin, a washer can be added to the detentions spring which is easily accessible inside the rear cap. The Prince valve detent spring looks to be buried behind the detent parts.

I am curious if adding shim(s) to the detent spring on the Prince valve will help keep the valve in the float position when using my front snowblower?

EDIT: the attached NH SB is apparently not for my Kayaba Valve. My Kayaba valve have a detent similiar to the Prince except that it does have 4 balls vs Prince's 2, and the Kayaba valve has a fifth slightly larger ball in place of the Prince's cone. The Kayaba valve has a very similiar spring to the Prince valve that pushes on the fifth ball in the same manner as the Prince spring pushes on the cone.

 

[toot77]

To add, the tractor has 540 hours and I believe it was pretty well taken care of prior to my buying it. I think the valve should be in pretty good shape. I did remove the rear cap on that spool and can see the back end of the detent assembly. It looks clean, I did not try to remove anything else until I have an idea of what may come flying out and what to watch for. I will do some checking in the area and see if there is a Prince rep who might talk to me about this.

 

[the old grind]

Between us we have cutaways of two different valves. One uses the center spool and one uses the spool opposite the relief valve for lift. Both show a similar location to add the .075" shim but IMO the SB is confusing compared to the cross-section view(s) we have.

#17 is the spring that the spacer would go (inside #16) behind/between #18, but on #7 spool vs #6 as shown above depending on which is lift. I can scan pics & a snapshot of disassembly instructions from the T1520 manual. (Section 35)

btw, My FEL is overdue for the same fix, so expect me to jump in soon. Should only have to remove the cover & one end cap. And THANKS for bringing this up with a thread title that's to the point and will let us get the news out there to others.

 

[rScotty]

To add, the tractor has 540 hours and I believe it was pretty well taken care of prior to my buying it. I think the valve should be in pretty good shape. I did remove the rear cap on that spool and can see the back end of the detent assembly. It looks clean, I did not try to remove anything else until I have an idea of what may come flying out and what to watch for. I will do some checking in the area and see if there is a Prince rep who might talk to me about this.

Thanks for the beautiful photos and diagrams. Looks like you washed it!

First of all, a couple of things caught my attention. My apologies for the initial digression, but it's a price you pay for hobby advice on TBN.

One initial impression is that the spool valve assembly casting is oddly crude compared to most Prince components - although the machining you can see on the spools and connections seems to be Prince's typical high quality. I wonder why that is?? It doesn't mean anything, just seems odd.

And secondly I am still fascinated by the way the designer using the Prince valve solved the problem of moving two spools with a single lever. It works, and is wonderfully simple. In fact it looks like like something from a vintage mechanical motion textbook - or an old issue of Popular Mechanics. Most single levers today use some sort of a rotating ball mechanism in order to keep the spool forces equal, but the version shown would certainly work.

And last digression is just aesthetic. When I look at the one-dimensional cutaway view of the Prince valve, and then compare it with the artist's exploded view of the KAYABA valve below it - the one with the A,B,C components - I am nostalgic for those days when mechanincal shop drawings included a real artist working at visualizing and drawing 3-D views of exploded mechanisms.

None of this would have been obvious without those great photos and scans. Thanks again.

Anyway, here we go. I agree with how "the old grind" descibes the functions of the springs, spools, and detents in that cutaway view. And I don't see my expected weephole. Maybe it is internal or built into the sliding tolerance between parts? Maybe so, we know there has to be some way to vent or drain the void at the far right hand end. Old valve sets had an external weephole to vent to the outside, but apparently not this one. Bottom line is that easy solution #1 is not applicable. And anyway, you took the end cap off and any problem - like dirt or even hydrolocking - would have been obvious if it was there.

Easy fix #2:
Before we go on ... can anyone tell me what that piece is numbered 8,9,10,11, & 30? in the LVTR series valve? Is that the PB sleeve? I don't understand it and need to make sure it is not a restriction on rotating the spool valve. The reason is that my easy fix #2 "revolves" around an assumption that the hidden part of the spool valve has radial symmetry - i.e. that the part of the spool within the valve casting as well as the spring and detent groves are a 100% lathe-turned part. If so, the only thing preventing the spool valve from rotating is the actuating lever fastened to the flat milled on the near end of the spool valve. .

So easy fix #2 goes like this: With the engine off and ALL pressure released from the loader, mark the top of the spool valve at the lever, then unbolt the actuating lever from the end of the spool valve. Now the spool valve should be able to be rotated within the bore. Don't move it in and out, just try rotating that spool valve however much seems reasonable to break up any crud and stiction it has from operating in the same positon for decades, then finally rotate it 180 degrees out from the original position and hook up the lever again.
What do you think?

rScotty

 

[the old grind]

The odd bits are a check valve that works with regen & float. (8-11 & 30) Seven pics in the manual show flow to cyls in operating positions for curl and lift. Each one shows flow through or around the poppet according to control position.

 

[the old grind]

Staying in float requires a cone & spring 18, 17 to hold the four balls into the annular recess in the cap and keep the sleeve 16 in position until manually retracted. We just need to shim up 17 for more push to hold the balls in place better. Can be done in situ & no further tinkering needed, really.

 

[dicktill]

Thanks for the beautiful photos and diagrams. Looks like you washed it!

<snip>

So easy fix #2 goes like this: With the engine off and ALL pressure released from the loader, mark the top of the spool valve at the lever, then unbolt the actuating lever from the end of the spool valve. Now the spool valve should be able to be rotated within the bore. Don't move it in and out, just try rotating that spool valve however much seems reasonable to break up any crud and stiction it has from operating in the same positon for decades, then finally rotate it 180 degrees out from the original position and hook up the lever again.
What do you think?

rScotty

I have an idea if @rScotty's fix #2 doesn't work. Almost certainly the cap on that spool is a soft alloy, not steel. If so, over time, the balls could easily have worn away the "sharp edge" on the detent groove. Perhaps all you need is a new cap.