TCV relief setting

[MattA]

Does anyone know if the later 4 digit tractors with the backhoe transaxle had the standard 2100PSI relief or if they were increased to 2400PSI like the loaders.

The 4 digit backhoes followed the loaders from 2100 -> 2400 -> 2750 -> 3000 over the years. It should be noted that the later 4 digit backhoes got 3000psi rated Eaton pumps instead of the 2500psi rated Parker HD pumps the loaders and early 4 digit backhoes got.

I should have specified 3000/4000 series. Good to know the backhoe history

[dhitching]

I should have specified 3000/4000 series. Good to know the backhoe history

Wow now I feel silly haha. I'll measure two of them for you tomorrow if I remember.

[dhitching]

Does anyone know if the later 4 digit tractors with the backhoe transaxle had the standard 2100PSI relief or if they were increased to 2400PSI like the loaders.

I should have specified 3000/4000 series.

With a small sample size of two, I measured 1800psi on the travel circuit relief for both my 4221PS and my 4223PS/PTO. Assuming the spec is unchanged from the 2100psi spec on the earlier 4000 series tractors, they're both off by ~300psi. I also measured the relief in the PTO for both tractors (spec of 2200psi) with the 4221 measuring at 2000psi and the 4223 measuring at 1800psi, I bumped them both up to the spec value.

Reminds me why the 4100s are so much better at ground work with their 2750psi pressure relief!

[Harry]

I own a few Case GT’s and the 446 lift with snow caster on always squealed when lifting. So when I bring this GT into the shop before the white stuff comes, I’ll be adjusting the pressure relief for the lift control. Amazing to ne the 644 lbh has no pressure relief issues, especially on the D100. It just digs away effortlessly which is way cool. Harry

[MattA]

Does anyone know if the later 4 digit tractors with the backhoe transaxle had the standard 2100PSI relief or if they were increased to 2400PSI like the loaders.

I should have specified 3000/4000 series.

With a small sample size of two, I measured 1800psi on the travel circuit relief for both my 4221PS and my 4223PS/PTO. Assuming the spec is unchanged from the 2100psi spec on the earlier 4000 series tractors, they're both off by ~300psi. I also measured the relief in the PTO for both tractors (spec of 2200psi) with the 4221 measuring at 2000psi and the 4223 measuring at 1800psi, I bumped them both up to the spec value.

Reminds me why the 4100s are so much better at ground work with their 2750psi pressure relief!

Did the 3100/4100 series use a different drive motor? I know they used a larger pump (12gpm?)

[MattA]

I own a few Case GT’s and the 446 lift with snow caster on always squealed when lifting. So when I bring this GT into the shop before the white stuff comes, I’ll be adjusting the pressure relief for the lift control. Amazing to ne the 644 lbh has no pressure relief issues, especially on the D100. It just digs away effortlessly which is way cool. Harry

I have a similar problem when lifting my Berco snowblower especially when it's in a snow bank. Another 50psi in the lift circuit might be enough to lift the Berco ok. The Berco sits more forward than a snowcaster does. I believe I can open the hood without hitting the Berco. Can't do that with my snowcaster.

[dhitching]

Did the 3100/4100 series use a different drive motor? I know they used a larger pump (12gpm?)

No, they still use the C33234 drive motor the "normal" tractors use, so theoretically they have a higher top speed. However the owner's manuals call out the AH tractors as having a SLOWER top speed than the normal GTs instead of the ~15% faster speed they should have. This wouldn't be the first time the owner's manuals have had errors though.

And yes, with the AH series dual section pump (like the loaders) they have an H31 for the "travel" section. This is the same 11.75gpm pump the conventional PS tractors use, but the PS tractors have the priority valve sucking 1.5gpm, leaving them right around 10.25gpm, just slightly more flow than the D27's 10gpm that the non PS tractors get whereas the other half of the dual section pump on the AH tractor just runs the power steering. The flow values get even closer under load.

It gets slightly more interesting when you consider the operating range of the pumps though. The D27 (non PS tractor) is only rated for 3000rpm and 2000psi, not the 3600rpm and 2100psi the tractors are spec'd at. Additionally, flow drops with an increase in pressure. So when you look at the actual flow rate of the pump at 2100psi and 3600rpm (data extrapolated for the D27 because they don't rate it that high) the D27 flows ~9.52gpm and the H31 (PS / AH, which is rated for up to 4000rpm and 2500psi) flows ~11.02gpm at the 3600rpm/2100psi point the tractors run at. So the 18% increase in flow from a D27 to an H31 is really only a ~15% increase under load, but you get a pump that's actually designed to operate at the pressures and speeds the tractor is set to, so maybe there's extra value there haha.

[MattA]

Thanks for going into the extra detail

Did the 4 digit loaders also use the same drive motor?

[dhitching]

Thanks for going into the extra detail

Did the 4 digit loaders also use the same drive motor?

The loaders use a different drive motor than the GTs. Unfortunately I don't have a great way to get displacement figures for the motors at this time.

If you know anybody that has that info I'd be very interested!

[MattA]

Sounds like the 3000/4000/4200 series pump is the weak link in turning up the pressure. I thought it would have been the differential bolts. I'm surprised the 4100 series has another 650PSI in the travel circuit.