Open center Closed center?

[hydroholic]

hydroholic
I'm going to clarify my statement that you referred to as sarcastic/chiding. All JD 2 cyl's were OC hyd's. Then with the introduction of the JD new Generation tractors JD had all of the models CC hyd except the 2 step children 1010/2010 that stayed OC hyd's. Then along came the 820,830 & early 2040(3 cyl ngines) which were OC. To my knowledge up until about 1992 all othe JD tractors built for N. American sales were CC hyd's and JD stressed how good CC was because their competitors didn't offer CC. Yes CC hyd has some advantages but when a hyd problem arises it can cause major grief. But to state CC is easier to add a hyd valve to is only true if one uses the correct valve. I hope this helps to clarify my previous statement.Jim

TxJim,

Well yes, it does shed a little more light on the history/background of JD and I can understand JD's desire to get a "leg up" on their competitors in the market. I worked for GE D/D (dishwasher & disposal) and we were always looking to 'up-one' on the competition. Sometimes we were, sometimes not.

Bottom line I'm not here to debate the merits of either system. CC and OC are what they are, nuff said. Point is, we (as novices) run into problems and shuffle over to our various "user-groups" and can usually find a solution to our need, wouldn't you agree?

Anyway, I feel we've 'kicked' that democrat down the road enough to now make room for other "less fortunate" tractor jocks and their problems. I'm still going to put up a few pictures for "show-n-tell" week.

hydroholic
sandbar w/fl

 

[Tx Jim]

JD did get a large jump on competition with the New Generation tractors and yes there are advantages/disadvantages to both types of hyd systems.

 

[Gale Hawkins]

Thanks for all the posted info. I knew our 1983 JD 310B backhoe was closed system but did not know what that meant.

 

[RickB]

JD did get a large jump on competition with the New Generation tractors and yes there are advantages/disadvantages to both types of hyd systems.

The fact remains that every tractor manufacturer that I can think of that built tractors with pure CC systems has moved away from that style. Hydraulic systems with hgh standby pressures rob HP, make unnecessary amounts of heat, and are prone to internal leaking over time.

 

[hydroholic]

The fact remains that every tractor manufacturer that I can think of that built tractors with pure CC systems has moved away from that style. Hydraulic systems with hgh standby pressures rob HP, make unnecessary amounts of heat, and are prone to internal leaking over time.

I guess I was blessed because my 1976 JD401-C from a local college auction has been great. No major leaks and it has been run hard, VERY hard.

And just for a little update on my 'new' CC valve and grapple arrangement. Apparently "my" hydraulics are a bit much for my design as I managed to break 2 welds and shear the 1 1/4" lift bar. Wow, I'm impressed, back to the drawing board for some "bracket" rearrangement. More later.

hydroholic
sandbar w/fl

 

[J_J]

You could add an external relief across the cyl, and set the pressure for less power.

Surplus Center - 1/2" NPT 30 GPM 1500-3000 PSI RELIEF VALVE RV-H4

 

[hydroholic]

You could add an external relief across the cyl, and set the pressure for less power.

Surplus Center - 1/2" NPT 30 GPM 1500-3000 PSI RELIEF VALVE RV-H4

J_J,

Looking at my Prince MB series valve, one of the notes says it has a relief valve factory set @ 2500psi @ 6gpm. And the instructions tell how to adjust the pressure. Thanks for the heads up. First I have to some welding.

hydroholic
sandbar w/fl

 

[Tx Jim]

hydroholic
If you lower a closed center relief valve to less than stand-by pressure then the lowered psi relief valve will cause the hyd oil to get extremely hot.

 

[Tx Jim]

The fact remains that every tractor manufacturer that I can think of that built tractors with pure CC systems has moved away from that style. Hydraulic systems with hgh standby pressures rob HP, make unnecessary amounts of heat, and are prone to internal leaking over time.

Rick
In my initial post referring to my brainwashing while attending a JD sales meeting what you stated was what I was trying to state. I guess what I stated didn't come across that way.

 

[Gale Hawkins]

I know on our 83 JD 310B BH the fluid gets hot quickly even on a cool day. After all when using the hoe at near full throttle that is 60 HP doing nothing but moving UTF so that is a lot of energy for the oil to deal with.