Hydraulic pumps

JB · Post 22 Mar 2006, 18:05

It seems like someone in nearly every race suffers a hydraulic pump failure. Can someone tell me whether or not the hydraulic pump is integral to the engine, or is it an external accessory? And where is it usually located?

DarkSnape · Post 23 Mar 2006, 19:26

Hydraulic pumps deliver high-pressure fluid flow to the pump outlet. Hydraulic pumps are powered by mechanical energy sources to pressurize fluid . I remember u that the power plant must have 95 kg and include the intake system up to and including the air filter, fuel rail and injectors, ignition coils, sensors and wiring, alternator, coolant pumps and oil pumps. Hydraulic pump it`s an external accesory

anna87 · Post 25 Mar 2006, 22:20

well this sounds pretty intresting............

DaveKillens · Post 25 Mar 2006, 22:35

It appears logical to assume the hydraulic pump is mechanically driven off the engine, rather than the gearbox. There has to be hydraulic pressure to shift gears. It would have to deliver high pressure and flow rates at all times, so it would be a gear pump, or a variable displacement swash plate pump. A gear pump is simpler, but less effficient, while a variable swash plate pump would be able to deliver pressure and volume based on demand, regardless of RPM. But of course, it is slightly more complex, and thus the likelyhood of mechanical failure is higher. But swash plates have been around a long time, they are very mature, and most likely pretty reliable under racing situations. Personally, I would choose a swash plate because of it's efficiency.

manchild · Post 26 Mar 2006, 00:09

anna87 wrote:well this sounds pretty intresting............

Welcome! Do we have another girl on this forum?

DaveKillens · Post 26 Mar 2006, 00:39

Hello Anna. Manchild, down boy, down. Does anyone have a bucket of cold water I can throw on him? lol

Sknguy- · Post 26 Mar 2006, 01:36

Hello Dave, I have experiences working on farming equipment and so I've worked on hydraulic pumps and motors before. I know about gear, vane and roller pumps but I'm not familiar with a swash plate. Is that assembly anything like a vane pump?

Thanks.

ginsu · Post 26 Mar 2006, 01:51

This is a couple of interesting quotes from Peter Wrights' Ferrari: Formula 1 book on the hydraulic systems

Several of the control systems on the car require a hydraulics power supply to meet the performance speccification in terms of force leveles and frequency response. Having installed a hydraulic system, it makes sense to use it for control systems that might not demand hydraulics; the hydraulic system is lighter than electrical systems, so using the hydraulic system and avoiding the need for a larger alternator and batter reslults in lower weight. As a result there are several systems connected to the hydraulic supply.

Fuel filler Cap
Brake Balance
Power Steering
Throttles and Trumpets (not anymore)
Clutch
Gear Change

Hydraulic Power Supply

The abex variable-displacement swash plate pump is driven by the right-hand auxiliary drive on the engine. The pump has it's own internal control system that alters the swash-plate angle to vary the displaced volume per revolution whilst maintaining the desired system pressure.

Max Displacement: 2.5cc per revolution
Driven @ 71.5 percent engine speed
Delivers 10.7 liters per minute @ 6,000 rpm; Max 32.2 lpm @ 18,000rpm

Interesting factoid:

If the driver works the steering hard while stabbing at the throttles and changes gear, it is possible that the flow demands could reach somewhere near the maximum at almost 30lpm. This rather wild driving is most likely to occur coming out of a slow corner when engine rpm is at it's lowest and the pump can only suppply 10lpm.

DaveKillens · Post 26 Mar 2006, 01:56

Naw, it's not close to a vane pump.
http://www.roymech.co.uk/Related/Pumps/ ... ement.html
The cool thing about a swashplate pump is that you can vary the engle of the swashplate while it's working, and thus vary the volume pumped. The trouble with a swashplate pump is that it's expensive. It requires precision machining, and it's a bit complicated to assemble and maintain.
Most pumps I know of vary their pressure and volume based on RPM. Of course, with a swashplate it too will pump relative to RPM. But just by varying the swashplate angle, which is very easy to do during operation, you can control the volume pumped. Things like a vane or positive displacement rotor pump require a reservoir and check valves to control pressures and volumes. And of course, noo matter what the demand from the hydraulic system, the pump is always trying to pump fluid when it's turning. A lot of energy is thrown away when a check valve opens to relieve pressure or drain back to the reservoir. But with a swashplate, you need more volume and/or pressure, just move the swashplate angle. Less, same rule aplies.

ginsu · Post 26 Mar 2006, 02:17

I have one question about the swash-plate. Does it need some sort of bypass? For example if the engine is at high rpm, but a low volume of fluid
is required doesn't the pump have to bleed that excess pressure off somwhere?

EDIT: I checked out your link and the pistons simply look to be at a shorter stroke when less volume is required, so that solves the excess pressure problem. Brilliant!

Sknguy- · Post 26 Mar 2006, 03:03

Thanks Dave, yes I had imagined that they would be quite precise and expensive pieces of equipment. Much more so than for agricultural applications, lol.

Ginsu, most, if not all, of these pumps do have some type of bypass system. For a trypical agricultural application the pressures are in the 3000 - 3500 psi range from a large tractor. And I know there are pumps that go well above 10000 psi, whatever those applications are for.

Edit: I forgot to thank you for the link Dave.

DaveKillens · Post 26 Mar 2006, 03:09

In theory, you don't need a bypass or pressure blow off valve. You just adjust the angle or the swashplate so that it is moving less, and less, and if zero is reruired, zero fluid. But as anyone as experienced as Sknguy who knows the real world, nothing works perfectly,and a check valve allowing bleed off of unexpected excess pressure would be built in.
If an accumulator is built into the system, then demand could be met in that situation. But then, a smooth, consistent driver would rarely put the car in that situation. But if was an engineer, I would have an accumulator built in. The last thing I want to have is a driver in trouble, crossed up, and suddenly finding his steering going away from lack of pressure.

ginsu · Post 26 Mar 2006, 05:50

You make a good point about the driver. Obviously, some drivers would be better at driving the car if they understand how the hydraulic system works and at what points it was most stressed. This makes me wonder how well educated the drivers are with the technical aspect of the car. I'm sure Schummie knows this all to well. But Massa? I'm not so sure. Although, I love Brazilians!

DaveKillens · Post 26 Mar 2006, 07:37

Doesn't it all go back to a driver who is smooth, minimizes violent pedal and wheel inputs, and avoids errors where he has to start sawing on the wheel?