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Reverse Direction of rotation - Rexroth A4VG
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I have a Bosch-Rexroth pump for a tiller used on a snowcat that do not have the same rotation as the engine. The pump is clockwise, but I need counterclockwise.
Do I need to change internal parts to reverse the direction?
Thanks for your help!
Johan
 
Posts: 1 | Location: Iceland | Registered: 26 January 2010Reply With QuoteReport This Post
Bourdon
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Yep you need a new lens plate.
You also need to change the rotation of the charge pump which depending on design, there is usually a wear plate that needs turning along with the cover that has the crescent seal in it.
 
Posts: 643 | Location: British Columbia, Canada | Registered: 26 March 2009Reply With QuoteReport This Post
Bourdon
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The pump is used as close loop? Then I guess only the charge pump internal parts need to be reoriented. If it is a modified pump for open loop, the valve place could have been modified already as well as the cover(inlet port bigger tha the outlet port. The swash angle pilot can be modified too.

Later...
 
Posts: 809 | Registered: 12 November 2008Reply With QuoteReport This Post
Bourdon
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quote:
Originally posted by maglub:
The pump is used as close loop? Then I guess only the charge pump internal parts need to be reoriented. If it is a modified pump for open loop, the valve place could have been modified already as well as the cover(inlet port bigger tha the outlet port. The swash angle pilot can be modified too.

Later...

The port openeings in the plate are symetrical, but the positioning of the ports (timing) and the lead in grooves (decompression) are different. The lens plate needs changing.

What is a "swash angle pilot"?
 
Posts: 643 | Location: British Columbia, Canada | Registered: 26 March 2009Reply With QuoteReport This Post
Bourdon
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oh...humnn...if it is symmetrical, could it be possible that the lead in grooves(as you call it) are present in both sides? Since the pump is classified as for use in a close loop, it is also bi-directional in rotation, but must follow the charge pump rotation if the charge pump is thru drive?

If the pump is A4VG, it can only be used in close loop? If it is then, if the posters application is for open loop, then the part number could not be used. The rexroth pump(with lens shaped) that can be used for open loop is A4VO and it is single output rotation...

I cant see the reason why there is a need to change the lens plate(used in close loop)...although I submit if that is really possible and is being done for quite sometime now...I have no more updates or more continous applications of this type of system, thats why I also doubt my opinion Smiler. Until I could see/disassemble this unit again, then I could easily recall/analyze the possibilities...

What I mean of swash angle pilot is the piloting of the control piston... I was just in a hurry to go inside the workshop that time I posted my reply/comment.
 
Posts: 809 | Registered: 12 November 2008Reply With QuoteReport This Post
Bourdon
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quote:
Originally posted by maglub:
oh...humnn...if it is symmetrical, could it be possible that the lead in grooves(as you call it) are present in both sides? Since the pump is classified as for use in a close loop, it is also bi-directional in rotation, but must follow the charge pump rotation if the charge pump is thru drive?

If the pump is A4VG, it can only be used in close loop? If it is then, if the posters application is for open loop, then the part number could not be used. The rexroth pump(with lens shaped) that can be used for open loop is A4VO and it is single output rotation...

I cant see the reason why there is a need to change the lens plate(used in close loop)...although I submit if that is really possible and is being done for quite sometime now...I have no more updates or more continous applications of this type of system, thats why I also doubt my opinion Smiler. Until I could see/disassemble this unit again, then I could easily recall/analyze the possibilities...

What I mean of swash angle pilot is the piloting of the control piston... I was just in a hurry to go inside the workshop that time I posted my reply/comment.


The pump has bidirectioinal flow, but that doesn't mean it is capable of bidirectional shaft rotation with regards to it's input.

There will be grooves leading into and out of both kidney shaped ports, however the lead in grooves are larger. The two different lens plates are timed differently.

Using an AA4VG90 series 32 as an example, the lens plate for a clock wise rotation pump is HU00650711/CW where as the counter clockwise lens plate is HU00650711/CCW

The oil used to swivel the swashplate comes from the charge pump.

The 'G' indicates cosed loop, are we trying to make this run in an open loop application as well as change the rotation?
 
Posts: 643 | Location: British Columbia, Canada | Registered: 26 March 2009Reply With QuoteReport This Post
Bourdon
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Ok Doug, one last question...

With two different part numbers of lens plate, that could confirm that two different rotation needs two different lens plate. If you rotate the lens plate 180 degrees, if possible(if dowell permits), would the timing be possible for use in the reverse rotation?

Thanks for the info.
 
Posts: 809 | Registered: 12 November 2008Reply With QuoteReport This Post
Bourdon
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quote:
Originally posted by maglub:
Ok Doug, one last question...

With two different part numbers of lens plate, that could confirm that two different rotation needs two different lens plate. If you rotate the lens plate 180 degrees, if possible(if dowell permits), would the timing be possible for use in the reverse rotation?

Thanks for the info.


You would have to machine a new dowel pin hole, and depending on series would need to cut a new notch in the side of the plate for the timing adjustment screw. You would end up with a properly timed plate, but the lead in grooves would still be on the wrong sides of the kidney ports. So short answer is no.

I don't have any A4V plates, but here is a picture of 20 series sundstrand plates. See the difference. If you rotate a plate 180 degress, it still has the same lead in groove.

 
Posts: 643 | Location: British Columbia, Canada | Registered: 26 March 2009Reply With QuoteReport This Post
Bourdon
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Ok, I got it... I was thinking that there are four lead in grooves(I am not sure if there is a design)...I'll try to study it...

I am not sure if rexroth kidneys are same with sundstrand... In a rexroth book illustration, the kidney has no partition, I'll try to find it out too...

Thanks again.
 
Posts: 809 | Registered: 12 November 2008Reply With QuoteReport This Post
Bourdon
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No they're not the same, I just posted that becuase I happened to have them and not A4V lens plates.
The A4V has lead in and lead out grooves, but the grooves are not the same.

They usually have a segmant in each kindey port, but the front running face is full port.
This rough assembly drawing shoes the segmant, but no grooves, it does show the timing notch on the side of the plate though.

 
Posts: 643 | Location: British Columbia, Canada | Registered: 26 March 2009Reply With QuoteReport This Post
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