What is a pump dump?

[LouNY]

All the manlifts I've had anything to do used cylinder locks. The more common use for tractors is on hydraulic top links.
They can be singles; these used to be common on out riggers and such. They require pressure to move in the unloaded direction.

And the more common in the tractors is the double;

When used in lifts they provide a safety function in that a deliberate operation is required for movement. A minor bump of a control will have no effect. a blown hose on the sensing side will lock the cylinder in position.

 

[BeezFun]

All the manlifts I've had anything to do used cylinder locks. The more common use for tractors is on hydraulic top links.
They can be singles; these used to be common on out riggers and such. They require pressure to move in the unloaded direction

Yes, all my cylinders have pilot operated check valves built right on the cylinder.

 

[oldnslo]

Beez
Do you also have the hydraulic schematics for that lift. With that we might be able to determine what valve or valves need to be energized for each function.

On photo 8933 I see three manual operated valves but I can’t tell if they also have electrical operation.

 

[BeezFun]

Beez
Do you also have the hydraulic schematics for that lift. With that we might be able to determine what valve or valves need to be energized for each function.

On photo 8933 I see three manual operated valves but I can’t tell if they also have electrical operation.

I attached the hydraulic schematic.
In photo 8933 you might be looking at the manual hydraulic hand pump. That's used if the system fails, you can lower the boom by pumping that by hand.

 

[BeezFun]

There are 3 other circuits on the logic diagram I'd like to understand as long as I'm doing this. I'm not sure it will help solve my problem but I'll be a little smarter:

• One is "Slew Motor Bypass" which I assume is to avoid too high a pressure on the hydraulic motor that drives the slew motion of the lift.
• The second is "Cont Boost" which must be an abbreviation for something, but I have no idea what.
• The third is "Dump Boost"

 

[oldnslo]

There are 3 other circuits on the logic diagram I'd like to understand as long as I'm doing this. I'm not sure it will help solve my problem but I'll be a little smarter:

• One is "Slew Motor Bypass" which I assume is to avoid too high a pressure on the hydraulic motor that drives the slew motion of the lift.

Are you referring to the "Slew override"(optional) valve? If yes I believe that valve is to bypass the slew motor and provide full pressure to lower or decent function to release the P.O. check. This is required since the valves are in series and if slew motor requires to much pressure you cannot slew and lower simultaneously.

• The second is "Cont Boost" which must be an abbreviation for something, but I have no idea what.

I see "cont boost" on electrical schematic but not sure what it relates to hydraulically.

• The third is "Dump Boost"

If, repeat IF I am flowing the electrical schematic correctly Relay 9 is energized which powers the dump pump solenoid S1. I believe the "flow Switch" which powers relay 7 does the same function.

My electrical knowledge is limited so the answers could be 100% wrong.

In studying the hydraulic schematic their may or may not be a pump dump valve on the DC unit.

On the electrical schematic are S1 - S8 limit switches or selector switches the operator controls? S1 - S4 show being tied to the out riggers so not sure what they are.


Hydraulically it appears that all of the cylinder movements are manual so if motor is running and dump valve is off the machine should operate.

 

[BeezFun]

Are you referring to the "Slew override"(optional) valve? If yes I believe that valve is to bypass the slew motor and provide full pressure to lower or decent function to release the P.O. check. This is required since the valves are in series and if slew motor requires to much pressure you cannot slew and lower simultaneously.

I see "cont boost" on electrical schematic but not sure what it relates to hydraulically.

If, repeat IF I am flowing the electrical schematic correctly Relay 9 is energized which powers the dump pump solenoid S1. I believe the "flow Switch" which powers relay 7 does the same function.

I think the flow switch ensures there is hydraulic flow. If there isn't, it shuts off the engine/motor so you can't damage the pump. It would make sense for it to also determine when the dump valve should close because if there's flow, the motor is up to speed.

My electrical knowledge is limited so the answers could be 100% wrong.

In studying the hydraulic schematic their may or may not be a pump dump valve on the DC unit.

I can't find one, and can't see any evidence of wires going anywhere it would be.

On the electrical schematic are S1 - S8 limit switches or selector switches the operator controls? S1 - S4 show being tied to the out riggers so not sure what they are.

S1-S4 are micro switches in the pads on the outriggers. If the pads become unweighted, the switch opens and an alarm sounds. This would happen for example if the soil is soft and the pad sinks down far enough that the tires start to take some of the machine's weight.
S5 is a micro switch that tells whether the boom is in the lowered/parked position. This allows raising the outriggers.
I don't see an S6.
S7 is a micro switch that tells when the slew position has reached it's limit.
S8 is a duty selector that determines whether the hydraulic flow is through the outrigger circuit.

Hydraulically it appears that all of the cylinder movements are manual so if motor is running and dump valve is off the machine should operate.

Yes, the problem is I can't get the motor to run unless I jumper it directly to the battery.

 

[oldnslo]

Looking at electrical schematic:
I believe RL6 & RL41 have to be energized to provide power to the coil for RL8.
I believe RL6 is powers by Selector Cage start switch.

I believe RL41 is controlled by S5 boom raised.

 

[BeezFun]

Looking at electrical schematic:
I believe RL6 & RL41 have to be energized to provide power to the coil for RL8.

That is very helpful. If it's not too complicated, can you explain how you figured that out.

I believe RL6 is powers by Selector Cage start switch.

agree

I believe RL41 is controlled by S5 boom raised.

Yes, and S1-S4 for the outriggers pads. I have no idea why they label those two logic paths as "Jack Light No 1" and "Jack Light No 2". Maybe on the other side of the ocean that means something obvious.

 

[oldnslo]

That is very helpful. If it's not too complicated, can you explain how you figured that out.

On the electrical schematic it looks like there is two options to power RL8.

on the schematic vertical locations are labeled A thru G and horizontal is 1 thru 10

Reference location 5 E:
this shows S1 - S4 NO contacts in series with jacks up so no power to terminal 108

Below information is based on RL7 not being energized:
Terminal 7 connects to contact on RL6 (I think, hard to read) Terminal 108 connects RL41 (I think, hard to read) Both RL6 & RL41 must be energized for this path to close and power RL8.

Once the outriggers are in position and S1 - S4 change state I believe RL8 is held active & RL4 is now de-energized.

Where are the electrical gurus when we need them?