Bosch 11240 Hammer Drill

[whejdak]

I recently took my 11240 Hammer Drill apart. I found that the piston has two O-rings on it. I have the 11240 Diagram and it doesn't show both O rings on it .
The diagram shows two O-rings close to each other, but I believe that one is for the piston and the other is for the striker next to it.
I would hate to replace only one ring and leave the other on it.
Any thought on the ring (smaller one and further from the head of the piston)

 

[whejdak]

I just saw a video showing the two rings. This gentleman, just ignored the smaller one and replaced the larger.
Never said Boo about not do it.
He has a lot of video's on U tube and does alot of repair on tool (he is from Irland).

 

[The Cobbler]

he is from Irland

I was going to suggest him, Dean Doherty

 

[whejdak]

Thanks, if you can get past his way of talking and can understand him, he is good.

 

[jack stand]

If you're "in there", replace any o ring you come across especially if you can size them by comparison. They are pennies if you buy an assortment.

 

[KnurledNut]

@whejdak
I am only seeing one o-ring:


It appears to be Viton, but could be HNBR. It would be good to replace with the same material.
165: https://www.ereplacementparts.com/parts/demolition-hammer/bosch/erp19503133/o-ring-1610210079/
Parts page: https://www.ereplacementparts.com/models/demolition-hammer/bosch/id791545/11240-0611240039/

 

[whejdak]

Thanks for your input. I do have the schematic parts layouts. The picture of the piston does only have the one O-ring.
But, looking at several video's that are out there, one can find a piston with two O- rubber rings on it. Mine does have two.
I have two of these drills. One is an 11240 model and the other is RH540M. I ordered a "Service Kit" for both units. Interestingly enough, I find that the kit for the 11240 didn't come with some of the parts that I thought would need replaceing. And, the kit from RH540M has those parts. So, I am stealing parts from the RH540M kit and using them.
What I don't like at all.......... It's up to you to determine which parts goes where. There is no paper involved with part numbers or a diagram showing where the parts go. According to Dean (Ireland guy) there is a paper in each bag. Maybe in Ireland there is but not in Wisconsin.
I bought the RH540M for $25.00. I put an armature in it (along with all the problems I talked about earlier) and it is hammering just like it should. I had the 11240 for some time. the hammer feature stopped. That is the one I'm working with now.
They are very similar in parts content.