Understanding my EC15B

[wowe]

Hello,

this thread is a compilation of different themes around the EC15B, where I think itīs not necessary to spend a own thread for them.

[wowe]

Understanding pressure measurements

In the section "(9122) Stand-by pressure" is a measure described to determine the delta-P = Pressure_P - Pressure_LS. The measure points are located at the inlet element of the control block. So the "LS" means "Load Sense". This I understand.

In the section "(9122) Checking and adjusting the pilot pressure" is also a delta-P measurement described: delta-P = Pressure_P2 - Pressure_LS". Pressure_P2 should have 32bar.

But here is the point of no understanding: I think LS stands for "Load Sense" but at this place at the pilot servo valve block "Load Sense" makes no sense.
I think the 32bar is the pressure for the pilot system, but what is LS?

Regards wowe

[wowe]

I viewed the doc again. It seems as that for the delta-P-measurement at the servo block really the load-sense is used. I donīt understand.

[v8druid]

you obviously have a variable flow/pressure pump.

the servo pressure is 'usually' supplied by a separate pump, usually driven off the motor's timing gear.
It may sometimes be bled off the Delta P with a reducer valve .... but is most often an independent pump.

the delta pressure is a constant pressure which is only low(ish) and develops as soon as the pump is turned over, as you start the engine. It's low, to not load the engine's starter too much and provides a pressure to initially activate the swash in the pump. there should be a Delta test point at the pump.

the load sensing pressure up / down strokes the pump according to the demand placed on it by the load sensing circuit .... it will be Delta P + pressure required from/demanded by the LS circuit, dependent entirely on the motion activated and the load placed upon it.

The LS line will have zero pressure at rest and only become pressurised, according to the motions demanded of the system
Hope that's of help

[wowe]

As I know there are two way to reduce hydraulic losses:

1. Open Center hydraulic
At open Center hydraulic the hydro-pump has a constant flow rate, because the pump type. The loss is reduced by adding a "load sense"-steered valve which opens a Connection between "pressure" and "tank"-flowback. When I look to the doc, my Volvo has this type of hydraulics.

2. Closed Center hydraulic.
At closed ceter hydraulics the uses the "load sense" to control the flow rate of the more complex and adjustable pump.


But nevertheless - my point of no unterstanding was the delta_p-meassurement at the pilot System. The pilot system is the presteering with the joysticks. What the hell makes sense to determining the pressure difference between the pilot system and the "load sense" which is located at the high pressure control block which uses the pilot system only to drive the control block valves?

[v8druid]

As I know there are two way to reduce hydraulic losses:

1. Open Center hydraulic
At open Center hydraulic the hydro-pump has a constant flow rate, because the pump type. The loss is reduced by adding a "load sense"-steered valve which opens a Connection between "pressure" and "tank"-flowback. When I look to the doc, my Volvo has this type of hydraulics.

2. Closed Center hydraulic.
At closed ceter hydraulics the uses the "load sense" to control the flow rate of the more complex and adjustable pump.


But nevertheless - my point of no unterstanding was the delta_p-meassurement at the pilot System. The pilot system is the presteering with the joysticks. What the hell makes sense to determining the pressure difference between the pilot system and the "load sense" which is located at the high pressure control block which uses the pilot system only to drive the control block valves?

I viewed the doc again. It seems as that for the delta-P-measurement at the servo block really the load-sense is used. I donīt understand.

me neither mate without all the doc.s you're viewing ..... what you are saying does not make any sense to me either ?

[wowe]

me neither mate without all the doc.s you're viewing ..... what you are saying does not make any sense to me either ?

I had tried to explain the theme with my words. I thought it is understandable... but it seems as it failed.

[ianoz]

I had tried to explain the theme with my words. I thought it is understandable... but it seems as it failed.

Wowe,whatever you are using to translate is doing a bad job.

[wowe]

Wowe,whatever you are using to translate is doing a bad Job.

Whatever Iīm using??!!??!! I use nothing except myself

At School I had a good grade in English - so I think Iīm like a native english writer...

2. Closed Center hydraulic.
At closed ceter hydraulics the uses the "load sense" to control the flow rate of the more complex and adjustable pump.

Ok - some could be written in a better way:

At a "closed center" hydraulic the "load sense" is used to control the adjustable flow rate of the pump.

[v8druid]

Whatever Iīm using??!!??!! I use nothing except myself

At School I had a good grade in English - so I think Iīm like a native english writer...

LOL you're a lot better than I am at German Boyo

Ok - some could be written in a better way:

with a "closed center" hydraulic system, the "load sense" is used to control the adjustable flow rate of the pump, by varying the swash plate angle.

Now that makes more sense ...... but we already know that ....... what is it that you are trying to ask?????

[wowe]

Ok - I make a final trial to describe my understanding problem: At the EC15-doc there is a delta-pressure measurement described. Delta-pressure means, that the difference of two pressures is determined. The one pressure is located in the Pilot control. And the other pressure is the "load sense"-pressure which is located in the control-block. I donīt understand the sense to determine the difference of this two pressures.

So this was the final trial...

regards wowe

[v8druid]

Ok - I make a final trial to describe my understanding problem: At the EC15-doc there is a delta-pressure measurement described. Delta-pressure means, that the difference of two pressures is determined. The one pressure is located in the Pilot control. And the other pressure is the "load sense"-pressure which is located in the control-block. I donīt understand the sense to determine the difference of this two pressures.

So this was the final trial...

regards wowe

The Delta P is the level of pressure generated by the pump on start up to overcome the bias/balance spring on the swash plate and keep the pump unloaded until oil is demanded and the swash is up-stroked.
there should be a dedicated port on teh pump to measure Delta P .... it will not show up in a service line.
The LS line upstrokes the swash when it senses a load demand at the main valve block .... the degree of upstroke is subject to the load placed on the LS line, etc.

I asked before ..... do you have a separate servo pressure pump ?? or is the servo pressure derived from the main pump?

Delta P is generally about 25 bar ..... mine on the hydrema is 55 bar (very high)

It's possible that the Delta P on yours is also your servo pressure, but I'd have thought that would affect your m/c's DeltaP's ability to regulate the swash accurately

I'm afraid I still do not understand what you are trying to achieve ??

Delta P will be 'X' bar
servo pressure will be 'Y' bar and neither should vary
LS pressure will vary according to the load
Main pressure will be LS + DeltaP at any given moment in operation/under load ......but the Delta P will not show on the gauge, only the load pressure
off load, main pressure will be zero and the Delta P pressure is only measurable at the dedicated Delta P port on the pump's swash control circuit

There are some very good you tube videos for variable displacement pumps and their functions .... there are some links in my thread ... probably about 3-ish months back