Today when I was pumping I got jammed up in my reducer, and the pump wasn't responding with the remote. I have to then jump on the deck and manually shut the pump off.  I reset the remote and see if it works, and the remote still doesn't work.  Then I try to pump using the controls on the deck of the pump.  Go to throttle up, and all of a sudden I see white smoke coming from the air intake stack behind the driver side of the cab.  Cant figure out what is wrong.  I go shut the truck off and take it out of PTO, then start her up again to see if the problem is fixed.  Still no response from the remote or manual controls.  Called my dad, and talked to my fellow operator, and they say that the engine REVERSED DIESELED on me.  The engine reserved on me because I was pumping slow with shitty mix, and a fin fish the size of a softball got wedged in my reducer. Today could have been really bad, and a lot of damage could have been done.  Defore today I didnt know a diesel engine could do that.  

Has this happened to any of you guys? What did you do? It was nerve racking, but no one got hurt, and I got her working and finished the pump.  Today was a huge learning experience for me.

sooo.... basically you're saying the engine started running backwards? did i get that right? lol if so that's a new one for me... glad to hear it all worked out for you! :)

With a very harsh mix it has happened numerous times that yes the diesel under strain will flip to reverse. I just can not believe you could not hear the engine strain and second, why with a harsh mix you would not be pushing at full throttle and low volume, and baby step pump so we always called it. You must be running a rock valve.

yep

Yes, the engine actually went into reverse. The exhuast actually became the intake.  I heard it jam before I actually heard the truck kick back in reverse.  I could tell something was very wrong because of how the truck sounded when I throttled it up manaully on the deck when my remote wasn't responding. And, yes, it is a rock valve. One of my biggest mistakes is that I was pumping to slow and should have turned my stroke up more, but it was an averaged sized fin fish that caused the problem.

It is a 1985 schwing 36/1200

I take it that when you guys talk of harsh mixes you are trying to pump 2,500 psi if you should no better even a 3,000 psi has it limits and is very hard on pump I have heard a rock valve will do harsher mix's but why, thats a job for TB  AND YOUR PUMP IS A 1985 MODEL.

The mix was a 4,000 psi 3/4-1" 1% calcium.  Only a couple conveyors in the northeast.

Old Detroit's and Macks were notorious for this. Happened alot with tractor trailers hooking up to loaded trailers. Happened to me when I was in a dump truck. I was stuck in soft ground and tried to get out on my own but when I rolled back I didn't get the clutch in time and it started running backwards. You did the right thing by shutting the truck off, because what happens is as the engine runs backwards so does everything else which includes the oil pump and it will actually start to fill the cylinders with oil and once that happens there is no stopping it until it runs out of oil or blows sky high. The good thing is that you now know it can happen and what to do about it. If it happens again just shut the engine off as quick as possible and restart it.

Good Luck.

I would think that a 4,000 psi mix would pump just fine do you guys have flyash up your way.

It is a Mack engine.  We have a ready mix company, and our mix is excellent compared to other companies around us.  It may seem crazy, but our ready mix company actually puts cement in the concrete.  There are plenty of fly ash mixes where we are.  The company forgot to add it, and it was suppose to have fly ash.  The mix is like pumping sand and 1" stone with gray paint in it.  Worst I have scene, but I am also still a rookie, and I am used to pumping really nice mud.

Well it's happened to most of us, and good on you for shutting down asap. Now your becoming an experianced operator, remember most issues come in threes, in pumping, add a digit to that. Un nerving maybe, but calm always wins.

I did know a diesel could go in reverse.. In the 50's !!!  Must be a MACK you are talking about...

Yep it is an mr Mack.  The thing that made that situation the best was staying calm and thinking clearly, and everyone on the job did the same.  People there were helping me as well and I had another pump on the way just in case.

Ive had cat motors do this also 

My Duetz will run backwards also.  It is running at a to slow of rpm and the engine lugs down and chokes then it catches it's breath and starts running backwards.  Freaked me out the first time.  Shut it down and started it right back up and it ran fine.  I just keep my rpm's up a little higher now.

I was told a long time ago, ALL equipment should be run full throttle...that's how they were engineered. The output or "end result" is controlled by hydraluic adlustment through valves and pressure relief, Anybody else do this?

The Only real thing I can adjust is my stroke/volume of concrete, but there are many situations on jobs where you can and can't run the truck full throttle.  I see what you are saying though, but running full throttle is hard on the equipment, especially an old unit like mine.

Well throttle up more, the pumps can damge also, and probably worth more than an inframe. But slow and steady winds sometimes just watch your pumps.

Our first pump was 1980 28M Titan/Elba with a flapper valve (i think that's what it was called), mounted on a GMC Brigadier with a 671 Detroit that would flip over to reverse every now and then. 

The only good thing about it was that it cleaned out the air filter to allow us to get a few more months out of it. 

The problem with the 2 stroke detroits was that they had very low torque (especially below 1500 rpm).  Combine that with being underpowered in the first place (175hp I think), and it was easy to get it to lug and flip over, even when running at full throttle.  Never did any damage, but the operator was never more than his 27' cord from the machine.

We also had an '85 putz c-valve with a 285hp Mack and never had it happen.  That was the last of the mechanical diesels for us.....

What is it that can dammage when running to little throttle?? I've been running low RPM (like no revs at all) with my pump  since I got this one a year ago.. It is total 2,5 years old.. I have the feeling the boom is getting slower and weaker.. If I use a+b section same time its almost doing nothing.. By the way I am reving up now and get the feeling I have to rev more and more to get the same effect.. I also tested with a mixer on a job where I could empty a whole truck on one place how fast I could empty him.. We calculated I was pumping 95m3 per hour. That was full throttle and volume and a nice concrete slump 220.. I should be able to pump at least 130 m3 ph..

Its a 38z JMBH 

hey boyz but how low is the throttle while youz are pumping for the engine to start running backward,ive never seen it but ive heard about it.

Dipstick, the newer machine probably no problem to run at lower rpm, older models would get pump cavitation, not enough spin in the hydrolic pumps can damage, we had the reich's and they were ran low rpm by a few operators, we replaced pumps allot, newr models are much better,labor machines, to the point of reverse is just to low. I alway go by those pumps we replaced.

When this happened to me I was probably running somewhere around 1200-1500 rpms.  Even with the throttle low or high, if a fin fish is coming through the pipeline it will get jammed either way if it can't go through the reducer.  Am I right or wrong? What I'm trying to say is that if it's going to jam or plug up then it will. 

 So what some of you are saying is that if I had been at a higher throttle this wouldn't have happened? Wouldn't the result have been worse if I were at a higher throttle?