How to increase HST relief pressure on a CK30

tinman955 · Jan 2, 2012

How much change in psi can a guy make before any danger, 200psi 500psi 1000psi?

What port can be used to check hst psi?

Tim M · Jan 2, 2012

It's been a few years but, sitting on the tractor looking down at the ports, I believe the left port is the forward pressure. The middle is the charge pressure (not what you want). The right one is reverse. It won't hurt anything if your monitoring the wrong port in the beginning. You'll see immediately which is which when you apply a little pedal.

Here are the details on the plug threads:

http://www.tractorbynet.com/forums/...rostatic-transmission-pressure-port-plug.html

I was able to get a local hydraulic shop to make me a hose for a gauge 0-5000psi.

And for the record to all you gear "snooty snoots" with my modified RV I was able to "spin the wheels to China"!

dfkrug · Jan 2, 2012

Tim M said:
I was able to get a local hydraulic shop to make me a hose for a gauge 0-5000psi.

Make sure you get a guage that reads at least 7K psi. AgriSupply has a
10K psi guage for about $15. A 5K psi guage is not going to be accurate
at the extremes of its range.

Tim M · Jan 2, 2012

What would be your guess as to the accuracy it's losing at say 4300 psi?

I think this is the one I have.

Bourdon Tube Pressure Gauge
Industrial Series Liquid Filled
Type 213.40

Products - Pressure Gauges - Industrial Pressure Gauges - 213.40 - WIKA Instrument Corporation

2ｽ? ｱ 2/1/2% of span (ASME B40.100 Grade A)

2% of 5000 is 100 psi.

dfkrug · Jan 2, 2012

Tim M said:
What would be your guess as to the accuracy it's losing at say 4300 psi?

I thought you were shooting for closer to 5000psi. I don't know what
the accuracy is of most cheap pressure guages, but in general they
are less accurate at either extreme. I would be more concerned about
EXCEEDING the upper range. A 5000psi guage is prob good enough
for measuring 4300psi, as long as you don't expect it to be much higher
than that.

SSdoxie · Jan 2, 2012

dfkrug said:
I forgot that I started this thread, TIN.

Kudos to Tim for making an adjustment, and measuring the pressures,
before and after. I have been meaning to get a 10,000psi guage to
measure multiple HSTs.

I may be quite easy to intall the CK35/CT235 RV in a CK30/CT230 as
well. I don't imagine the part costs very much....

The current CK35/CT235 has a slighlty different hydro than the 27 & 30. The drive reliefs have the replenishing check valve incorporated into the the relief on the 27 & 30 the replenishing checks are ported internal. The relief valves will not interchange.

Tim M · Jan 2, 2012

Ok. So what about the rest of the HST internals? Would it be safe to take the CK30 HST relief pressure up over the 3950 psi spec to the CT235 spec of 4260 psi?

SSdoxie · Jan 3, 2012

I don't know what the purpose in design was or is. I suspect it is lower on the 27 & 30 due to HP to help keep the engine from dying when under max load. All 3 models are the same frame (weight) & gear reduction so the lower HP of the of the 27 & 30 may not be enough and you could get more engine lugging especially at lower RPM.

dfkrug · Jan 3, 2012

SSdoxie said:
I don't know what the purpose in design was or is. I suspect it is lower on the 27 & 30 due to HP to help keep the engine from dying when under max load. All 3 models are the same frame (weight) & gear reduction so the lower HP of the of the 27 & 30 may not be enough and you could get more engine lugging especially at lower RPM.

I think DaeDong made the wrong trade-off in the HST design. If they
designed for a higher pressure, the weaker engines would just not be able
to move quite as fast under the high loads and traction. The Kioti HST
is the first one I have used extensively that will go to relief in low range
and high loads/traction, without spinning the tires. My JDs would never
fail to spin tires in low range/hi traction situations. My B21's engine was
low power, and a bit tired. It's HST would not go to relief in low range,
ever. The engine would bog rather than spin tires. A newer B21 might
not do that.

Tim M · Jan 6, 2012

Definitely an under designed HST. I would much rather stall the engine than hit relief.

Let's assume your not comfortable running your CK30 HST relief pressure at a higher than spec psi.

What other options are there?

Can an entire HST unit from a CK35(CT235) be put onto a CK30?

Anybody know how much an HST unit costs?

Can any of the downstream gearing be changed?

Not interested in smaller tires(less ground clearance).