My great-grandfather left home at 14, and no-one today knows how he managed this, but somehow learned how to run an RD6. That same year he hitched into the rough project of building the Fort Peck Dam in Montanna, living in a tin and plywood shed at night and driving one of these every day. When I was little - maybe 6-8 years old - he stopped his truck one day to show me a Caterpillar RD6 hauling big lumber like your opening shot in a forest off of Highway 101 on the Oregon Coast near where he lived. He told me about how much he loved driving it when he was a young man, and to this day if I have a chance to stop and listen to a big old Caterpillar tractor, and no-one is in the car with me, I will stop and listen to that amazing sound and my amazing grandfather is there with me. Thank you for making this video on my birthday; I'm about the same age he was when that happened.

I love cool shit like this when it randomly gets recommended to me lol

"When this thing really lays back, gets under load and starts cackling." Well said.

If it ever threw a rod it won't be shrapnel it would be an artillery shell.

4 years of diesel school and six years in the shop. Never have I heard anything explained so simply and so thoroughly. Well done.

I've been a heavy diesel mechanic all my life. Extremely excellent demonstration and narration to answer the viewer's questions. You should consider teaching at some level.

As a retired CAT&CUMMINGS knuckle buster I tell people quiet often that HP doesn't do the work TORQUE is what does the work!!!

This RD6 will be running perfectly a hundred and fifty years from now. Great video, Cheers !

That was the clearest explaination of HP vs torque I've heard to date.

Excellent tutorial. One camera, one man, one machine got more information across than most would with fancy graphics or recycled footage.

I just love videos like this - someone who really knows and loves their subject, explaining it clearly and concisely. This is fascinating.

I appreciate a true craftsman who not only can operate, but repair and most importantly explain the engineering involved. I found this channel completely by accident but now t has quickly become one of my favorites!

One liter is 61.0254 cubic inches. Ten liters out of 3 pistons!

I just love the sound of that old tractor. Like some others, I didn't know CAT made 3 cylinder engines either. I sure am glad they did. They have that wicked sound. Great video!

You really taught this well. Loved your analogy in explaining torque vs HP. Good job.

The first tractor I ever ran was an RD-7. We used to joke about how you could lug it down until you could count the strokes. Thanks for posting.

Awesome explanation I worked at a gravel bank years ago and would reclaim with an old D8. You could count the fan blades go around she'd never stall. Thanks for bringing back memories.

So ironically, it's actually quite under-square, making it technically a very big small bore. Very cool. Thanks for the video.

Incredible engine and explanation ! The engineers really knew what they were doing back in the day, this was also before pollution controls where the only thing that really mattered was brute torque and reliability.. It will run almost forever ..Those days are gone.....

Thank you so much, my father Russell C. Shepherd, S Sgt., was a Sherman tank commander who volunteered for the Army in October 1941, landed on Normandy Beach and fought the Nazis all the way to Berlin. He was a farm boy, Second Armored Division, 702 Tank Destroyer Battalion, Company B, engaged one on one with a German MarkIV King Tiger tank and destroyed it October 1944...also received numerous medals...farm boy to war hero!

Great vid very, very good explanation. I've worked on locomotives for over 25+ years, on everything EMD made, GE, and ALCOs as well. Best engines ever? The 251-C, D, E series from Schenectady! Cats...love 'em too. Worked on 'em in fishing boats as engineer on main power, and aux power plants. Greatest marine diesel out there bar non!

if i had the cash i would buy a dozer and some land and just push stuff around.

My neighbor had one of these when I was a kid, it would lug down to what sounded like about 200 RPM - maybe less! Low speed, high torque engines make my soul sing - that's REAL power!

What a torque monster; you don't need RPM with the bore and stroke that's there with that beast. With a minimum of servicing these engines can last for a lifetime and more; old technology at its best. I enjoyed this video and no I didn't get bored. In fact you've got a new subscriber.

"Those who can, do. Those who can't, teach." You do a fine job doing both. You're obviously a skilled mechanic, and you're a better teacher than most I've experienced in my lifetime. Kudos!

I am a big fan of slow turning diesels. this one is my new favorite.

That's the best explanation of the difference between torque and horsepower that I have ever heard and understood it rightoff

Thank you for the great demonstration and explanation! I love those old heavy, slow turning engines! Amazing torque, yet horsepower so modest from the old engines.

I had the chance to run a D8 about 20 years ago that if memory serves me right was built in 1947. After running a newer version D6 from the early 90's it was really something to fill the blade of that D8 on a long push and feel it put it's head down and work. That D6 was nice with all the newer technology but it was a screamer and burned more fuel for the same amount of work at the end of the day as that D8. My John Deere two-cylinders from the same era share the same concept of torque and low RPM to get work done. My D has a bore and stroke of 6.175 X 7 (501 cubes) at 900 RPM, 29 draw bar, 42 belt hp. My 820 diesel is 6.125 X 8 (470 cubes) at 1125 RPM, 67 draw bar, 72 belt hp. Those old timer engineers understood big bore and torque and put it to good use, probably one of the biggest reasons this old equipment has lasted as long as it has!

Didn't used to be drawn to this but I love motorcycle engines & marine diesel engines. This RD6 information is valuable learning material. I am probably not alone in saying " I want one"!

My maternal grandfather, both my uncles, & my youngest uncle's surviving sons (my cousins) have been moving earth w/equipment similar to this for a combined total of close to 100 years! I KNOW mu uncles & grand dad are up there right now watchin' this awesome vid! Thanks for posting!

My great uncle was a foreman on a farm out here in San Onofre California back in the in the 50s. He was like my Abuelito or Grampa he would put me on his lap pulling out of the tractor yard on his way to the field or doing some road clearing after a heavy rain. I dug out some old pics and this looks like the same "Beast" lol Yes we had and still have farms in California. I love anything mechanical thanks for the awesome video as soon as i saw the pic on the video it brought back memories of my Uncle Ernie so thanks for that too.

My favorite part is at the end when he takes his stump out for a walk around the property lol

I saw a printed saying one time that described it as: Horsepower is how fast you hit the wall, Torque is how far you take the wall with you. thought that was fairly clever in a simple way 😊 really enjoy the CATS !

in few minutes this man shows all the details needed ! Amazing presentation mostly because he knows what his is saying and he loves classic models which means he knows what is best

That is Mahoosive!! Super long stroke and low speed! What a beast.

This is the first video I watched from this guy and boy do I wish more KZfaqrs explain things as well as this man. Even brought out the manual and gave us numbers with interesting facts.

That Engine is indeed a thing of beauty thanks for explaining Regards Steve

Used to work in a gas processing plant. Had RA 8 Clark two stroke engines. They had 880 HP at 330 rpm. With a 5 FOOT stroke and 28 inch diameter pistons. Had 6 of them on the floor. When working right they would put you to sleep. But if something happened to one of them it would bring you our of a dead sleep. They all had a common header and if tou did not catch it when one went down, they all went down. But you could catch it if you got the bad one shut down. Things took 55 gallons of oil for fill and used 3-5 gallons in 24 hours. Man, loved those engines and that sound.

My grandfather operated those old Cats his whole life. Thank you for letting me hear it again.

Same bore and stroke as a John Deere model R, which was rated to 54 HP@975 RPM from Two Cylinders. Ok, now I want an RD-6

You sound so smart sir. Very rare nowadays. Have a like.

Nice to see someone that appreciates these old machines and still works them

Can't rember exactly what year. Started with 40 and a B&G buggy pushed by RD 6, I beleave was a 1935. Was in diapers as I road in my grand father's lap while my dad pushed to build farm ponds. Years later after granda death, found a another RD 6 and replaced the old 40. With the two 6 cats as a doubled puller in high school, I continued building ponds for a few summers. The sound is heavenly still brings back so many memories. Wish the old man could have been around. He would have be proud. Wish I was still able to get out there. Thanks for you time and efforts with the video's. Means so much .

Another Squatch253 school-day! Loving these lessons, and wishing everyday was a school day like this...

I love the sound of big bore cats when they are lugged down and pulling hard that chop and echo in the exhaust just sounds cool and tuff to me, it kinda like the inverse of a screaming Jimmy

You couldn't give a better explanation on the subject and more general info , thank you !

As of this date, 173 dislikes. Why??? What's not to like? A very straight forward explanation of the question at hand. Not boring. Not lengthy. Great information with Factory proof of authenticity and accuracy. What's not to like?? Nice job Squatch! And thank you.

Informative.down to earth . Nice guy. Well planned presentation. Best if seen for a long time.

I used to work on an old direct reversing Superior diesel 14 1/2" bore X 20" stroke. Idle 125 RPM, full speed 350 RPM. Sweet sounding engine.

Man I am 43 and worked for a big paving company out of NC . I remember them pulling out this old rd8 . The fist time I seen that thing I was astonished at it mass compared to the d11 . The old guys had it brought to a job to use as a pusher because the newer machine couldn't get it . When that 70 year old man got on it he looked like he was taking his mistress out one more time . Even as a young man I knew I was whitnessing something special . And boy that thing was amazing . All the old guys stood and watched as it out performed the new machines .

First video I've understood in months! Thanks! For what it's worth, the Triumph triple I rode was incredible.

We had two RD-6's on our farm in South Florida, Both had the three cylinder engines. Thanks for sharing this video.

Excellent description of torque v.s. horse power.... Caterpillar is amazing.... I wish they had ready replacement parts for those old tractors.....

Straight up low end GRUNT!.......when she's up against or hooked up to it, something is coming loose or breaking . Very cool.

Love the distinctive sound of cats ,very well explained!! 👍 I remember my dad's d4 and old John deere! Big pistons & long stroke = big power!

Once again I'm watching every delicious moment of these old dozer vids...LOVE IT!!!

"Now I'll show you what the RD6 piston looks like" ... >clonk< ... Man, that thing is a monster!

Great video! One of my earliest memories was of riding one arm rest of our old Cable 8 with my great uncle driving. I remember being scared witless and loving every moment of it!

Very good explanation, back in the mid 80's I set a cat engine in a D8 dozer with a crane I was operating at the time, Man that engine was big, was talking to the mechanic and he said the same as you very low RPM, Great video keep it up

Gotta love the slow turning cat engines.

Great description, also the super low RPM allows more time for the fuel to burn, running them faster causes unburned fuel to be exhausted before its heat can be used.

Really cool! Spent many hours (hundreds if not thousands) dragging a chisel, disc and cultivator on one these RD6’s up and down hills, side hills.. my uncle would never let me start (hand crank) the pony motor..said it would rip my arms off if I didn’t do it right. But I remember dragging a small chisel plow to the top of the field, on a hill, lugging that thing down so much you could almost count between the combustion strokes.., making a turn was a very physical operation..pull in the steering clutch, stand on the brake on that side, bring it around, reduce power and shift it a gear up for the ride down, barely slipping the main clutch, trying not to grind the non synchro gears, throttle her back up in one orchestrated fell swoop of the controls.. and that tractor was made in 1938(?), forty some years old at the time. Along time ago..brings a tear to my eye. I understand now why my grandfather would give me the eye when I was being hard on the equipment. Enjoyed seeing this, thank you!

Excellent video. I'm an old coot and can remember the sound of these machines working, even though I'm not mechanically gifted.

I don't even like tractors or knew what a D6 is. But it was such an amazing, informative video. Subscribed.

Great explanation thanks. I had an old D-4 Cat once. Early 40s I think. Two cylinder pony stated a 4 cylinder diesel. The most ingenious thing on that old tractor was that exhaust from the pony passed through the intake manifold of the diesel for cold starts. What a simple but effective idea by Cat.

As a foreigner, it was a pleasure to watch this video. Very very well explained. Thank you for making the effort to explain a big bore diesel.

I've been pushing with my old d6b today I love watching your videos. Too bad they don't build these old cats again 👍👍👍👍👍👍👍👍👍

WOW! This is a great video!!! Thanks, Squatch253! I'm impressed! Like an old Farmall M tractor, you can't beat vintage machines...they were built to last for generations...contrary to the electronic controlled stuff of today with owners manuals of 4,500 pages, that will be dead in the water a generation from now. Also, EMP will most likely not effect pr fry the old school machines...and they will keep on ticking....

Grandfather had two D-6's. I guess I can still operate one of them, 50 years later. Thanks for the ride, at the end.

"I hope I didn't bore you".... This was one of the most interesting videos I have watched in quite some time. Absolutely loved it.

Toby, Great explanation ! Most interesting to learn about. Love the sound of that big old 3 cylinder working ! As always, Thanks for sharing ! Never a dull moment at your place !

A VERY good explanation from a younger old mechanic. As a child I watched diesel take over, there are praises and complaints for both. But my propane tractors don't require as much maintenance though it takes a little longer. Take care from Oklahoma, Mike and Vee

I generally have no interest in old bulldozers, but this came up in my feed, enjoyed it, well explained and pace of information delivery was good. I found it pretty interesting from the start. Great video, much appreciated.

i just love the sound of these old cats!

I always loved the sound of those large bore diesel engines. Kind of like the old mack trucks with a max rpm of 1000 rpm. They outwork newer engines all day long for the small HP they had

Don't know if it's been said but that first audio sample was very high quality. Had a nice surround effect. Sounded natural. Dude has a good mic or two for sure. 👍

This man is extremely intelligent. I have always known the difference between torque and horsepower. And he basically made my description into words and dumbed it down to the point that non mechanical people would probably understand...

My buddy "David Floyd Smotherman" (RIP) worked for our county department. He said they built a small fire underneath a RD6 in freezing weather to get it started. Strong equipment!!

That Cat RD 6 brings back memories of my dad in late 50s early 60s yep he ran a D 8 doser and in 65 he bot a komatsu.front end loader but he always raved about the cat.i still have his cat brass belt buckel. Grate vid on the RD6.thanks.

Wow, truly an impressive old-school engine design...really good interesting video!

I'll never hear one of these the same way again! Thanks Squatch.

When I was in the USAF I saw power production guys standing on the crank with a long micrometer, measuring out the cylinder walls of a giant diesel generator. Talks about a low rpm. The generator turned by the engine was enormous.

Great video and thanks for posting. Love to hear these old diesels, you can really tell it’s got power by just by the sound!

I was not expecting the size of those pistons you pulled out. I was surprised how big those things were, and that's comming from a guy who works on 35 and 3600s. I don't know much about the tractor side of things. That's amazing how much power those things are pushing at a rpm range lower than my cars idle lol

Interesting, informative and educational. Always a pleasure to listen to somebody who knows what he’s talking about talking about something he likes.

How in the world does 65 people dislike? It’s a good video, historic machinery, and clearly explained. Props to you squatch, good job.

Best explanation of relationship of torque and horsepower i ever heard. Excellent job!

Amazing!!! The learning curve in my life has expanded exponentially. Thank you for sharing.

About 30 years ago a guy I used to know bought this beater bulldozer that I believe had a 2-stroke diesel engine. The dozer was all worn out, but wow did that engine still sound great! I loved the sound of it.

This video randomly appeared in my homepage recommended section. I'm really glad i watched it, great and fascinating video.

Excellent video! I stumbled upon your video and out of curiosity, I watched it. Now I find myself wanting one just because the RD6 is so impressive! I would never use it but what a great investment!

Thanks Professor Toby! I am glad you took the time to bring class into session.

Like the old English tractors , single cylinder, the stroke so long the front end tries to bounce up and down at idle! I loved this video!!! This thing reminds me of the time my dad's wrecker broke down, we pulled it up a gravel hill, with a 59 Chevy truck, I was working on for my first car, it had 33*12.50 15" on the rear, 350, straight headers, it pulled that heavy wrecker up the hill, it sounded awesome, about 2500 rpm, full throttle, it left trenches all the way, posi, it was hooking with some spin, you could tell it was doing work! I miss those days, great video,

That was 13 minutes of my life very well spent. When I was young I worked on a cattle ranch as a farmer and used all manner of diesel equipment. I ran a D6 on occasion (not the same tractor as a RD6 I am quite certain). It was a beast (all mechanical clutch and brake) but what a workhorse. The JD tractor I used only had 57 HP and I always wondered how it could pull so much with such a small amount of power. I am 62 and now I know! Thanks.

Great & informative! That piston/rod assembly was a monster!

411 lbs of torque by my calculation. That's a beast!

Love to see the tractor working after the explanation

This is the kind of stuff that makes you love KZfaq. Learn so much each day. Thanks for sharing the wealth.

No boredom here! Thanks for the tutorial !!