Cat 374 Excavator build
 

G'day people . I have a few questions to ask , but i thought i would share what i am doing . After downloading the closest drawings of a 374 i could find i started to copy it . I use Alibre design to do drawings ( cad ) and realized pretty quickly that to make the track links how i wanted , i would need to get the old cnc running . I had plans to machine it all on the old cnc, but with old controllers having issues , i just managed to get all the track links made , literally in time before the cnc lost all settings and programs due to a memory back up battery failing .
So the track links are made on cnc and took about 4 hour to do both sides and i had 5 links in each piece for a total of 96 links .. They are 90mm wide.
I used m5 grub screws for the track pin. All i did was to machine the thread of them , down to 4mm - leaving 5mm of thread on one end . Screw in and locktite . Nylon washers between the links also .
I do not have the patience or skill of some of you guys but it is my first attempt .
Some photos of the track links , track frame ,and other stuff . I have made my own valve , but fear i may have made the rotary valve faces too big - at 24mm dia and will have problems with pressure pushing them too much and possibly making it impossible to turn ?- we will have to wait and see . Although i am thinking of remaking the valve with thrust bearings behind the rotary disc to combat this . I have 15kg servos , but am still seriously thinking of remaking .
The main reason for the size of the valve is i have all 4 cylinders at 20mm bore , using 4mm id pipe and fittings as i do not want it to be slow because of flow issues ..
Which leads me to my first real question , what size pump to use ..anyone have ideas on what pump to buy or should i make one . I am looking for an idea of pump size others have used with similar size cyls .. Cheers guys .

Re: Cat 374 Excavator build
 

Some more photos .

Re: Cat 374 Excavator build
 

Sounds like a neat project, I can't see the attachments. Photo bucket is popular here on the site...

Jim

Re: Cat 374 Excavator build
 

Re: Cat 374 Excavator build
 

A quick video of the track frame testing ,, a little fast perhaps , but still haven't dropped the throttle end points down yet .
https://youtu.be/Ipg8mdQlO1U

Re: Cat 374 Excavator build
 

Very nice! I love those track pads, which I could have made something more like those for my crane undercarriage project.

http://i12.photobucket.com/albums/a2...psh8caeitr.jpg

Do you have any pictures of parts setup on the mill?

Jim

Re: Cat 374 Excavator build
 

A great start with your project 374. :cool:

A Jung hydraulic pump is a definite must... the 900ml/min shown on this page, I think is not enough flow for 20mm pistons, especially having dual 20's on the boom, you might to change the boom cyls to 18mm. Send these guys an email to see if 1200ml/min pump is available.

http://shop.premacon.com/index.php?cPath=35_80

Re: Cat 374 Excavator build
 

Thanks guys , i think you are right Lil Giants . i may remake those cylinders as they are 4140 drilled and reamed so one of them has not got the finish i would really like And it heavy ) - i tend to over strengthen things a little :) . So maybe resize the cyls is an option .
Yes Jim ,, well sort of , i am a bit lazy for having taken pics along the way , but here is a video of the finishing contour pass of the bottom of the links , It is an old machine , but when it was working was lots of fun .
https://youtu.be/Nob_dIiwMaE

Re: Cat 374 Excavator build
 

Looking good! What scale are you building too? It looks huge! Do you have an idea what the finished weight will be? Keep up the good work

Re: Cat 374 Excavator build
 

It is supposed to be 1/10 .From memory the track frame , carriage and centre bearing hsg ( without bearings ) is about 15kg . And what you see in the photos at the moment total is about 41 kg , with more stuff to go ,, :)

Re: Cat 374 Excavator build
 

Lately it seems dual pumps are becoming more the norm on large constr models, and yours being 10th scale would certainly have the room for it. Perhaps dual 900ml/min, one pump for the boom & the other for stick & bucket. Keep your 20's on the boom.

Re: Cat 374 Excavator build
 

Like Joe said try dual pumps . I'm looking at putting dual pumps on my 1/14th scale 385's . Jung fluid makes them . There is a German reseller that sells them I just can't recall the name at the moment . :o on the other hand looks great so far :)

Re: Cat 374 Excavator build
 

Did a little bit more , Started the bucket and the engine cover . I am maybe an idiot , or just a cheapskate :) I think 2 Jung pumps will cost too much as so far i have made what i have , using materials i have had for years and only spent money on a few motors and some fittings so far .
Any way back to my "cheap " idea . I have been thinking of modifying a motorbike engine oil pump , But i will start experimenting tomorrow - the theory ( in my mind at least ) says it should be doable ,, we will see . I will let you all know how that goes :)
http://i12.photobucket.com/albums/a2...ps92eafqgy.jpg

http://i12.photobucket.com/albums/a2...psdpie41ar.jpg

Re: Cat 374 Excavator build
 

Wow! Are we related somehow?lol The machine looks great and I totally hear you on the cheap thing. I ended up buying a Jung pump for my 1/10 Volvo EC300D but only because I was impatient waiting for my father in-law to machine the case for my Honda 50cc oil pump gears. I ended up using the "Honda" pump in my Tigercat 630D and it works OK. I'm not sure if all motorcycle oil pumps share the same profile but the gear teeth are very round and course. My pumps seem to move a lot of volume at low pressure but as the pressure comes up they are not nearly as efficient. Having said that, they do work though! I used to mess around with Honda 50's a lot so I had a few stock oil pumps and that's why we used them. The gears themselves are very close in size to the Jung pump I bought but a much different profile. If I did it all again I would spend the money on the Jung but the other type will work. You may just find that it's not very efficient. Hope this helps. Keep the pictures coming!

Reg

Re: Cat 374 Excavator build
 

A bit more on the bucket .. Yes it is Ali , i do not expect it to last forever , but it should dig a few holes before it needs replacing :) Now onto playing pump games .
Oh thanks for the advice RCP57 i am using a 125 oil pump and may try a big road bike pump if it shows signs of promise .. :)

Just a few photos of making the bucket side plates , a cnc would be really handy and save a new set up for every angle , oh well
http://i12.photobucket.com/albums/a2...pseut0cxwy.jpg
http://i12.photobucket.com/albums/a2...psgudpicya.jpg
http://i12.photobucket.com/albums/a2...ps8ajvgqpo.jpg
http://i12.photobucket.com/albums/a2...psk4ntgpxq.jpg

Re: Cat 374 Excavator build
 

I'm sure you will get a pump to work just fine. Just remember that the bigger it is the harder it will be to spin and that will take more motor/battery power reducing run time.

Re: Cat 374 Excavator build
 

I just went through your photobucket. Wow big tough machine I like it! I would have never thought that a little oil pump out of a motorcycle could build up a high enough pressure especially for a bigger build like this one. Nice job :D

Re: Cat 374 Excavator build
 

This is the pump i will try , i am told it is out of a 125 4 stroke . I have just done a drawings for the inlet-outlet hsg with an internal bearing support as the original was plain bearing and added a seal on the output shaft as previously any leaked oil stayed inside the motor and was probably used to lube the input shaft in the plain bearing .. .
RCP57 has given me hope it will work ( maybe not the best ,,, but ) . If nothing else it will cost me nothing other than time to find out ,, plus i find it interesting :)
http://i12.photobucket.com/albums/a2...psmitnztfn.jpg
http://i12.photobucket.com/albums/a2...psvmcdjjty.jpg
http://i12.photobucket.com/albums/a2...pssnttyeot.jpg

Re: Cat 374 Excavator build
 

Is that out of a Honda by chance? It looks exactly the same as the 50 pump other than the gears are thicker for more volume. See what I mean about the rounded teeth? I don't think this works well for extreme pressure and is probably why the Jung and other high pressure pumps have smaller, sharp teeth. I am able to get 250psi out of the oil pump fairly easy but beyond that the volume drops off significantly as the pump starts to slip. Hopefully you can do better with yours and as you said it is no loss to try other than your time. If you can make it work then you can say that you did it all on your own as well which is worth something in my mind. I don't know if you have access to one cheap but you may try finding a convertible top pump from a car. I bought one when I built my Volvo but didn't use it because the motor sucked juice like crazy. Inside though, it had gears almost identical to the Jung pump. It might be worth a try getting one for the gears and then your pump will for sure make the 400-500psi your machine will likely need.

Take my advise with a grain of salt though. I'm not a hydraulic expert by any means.

Reg

Re: Cat 374 Excavator build
 

One guy on here, i believe it was a 10th scale excavator, but he was attempting to ise a fuel pump out of a detroit di diesel! Just somthing that might intrest you. Maybe you can mess with that a while.