Stabilising a Rubber Duck.

[Hugh Jaleak]

Not sure if this is right place to post this question, please feel free to move it Mods if you wish.

I drive a Cat M315C fitted with Cat G315B grab, grab by itself weighs 1.25 tonne. Not surprisingly she's a bit light on her heels at full stretch, especially sideways working, and thats with an empty grab. Pretty sure Cat spec says this attachment on a machine free on wheels is not recommended. Does give stability issues!!

Machine is fitted with 2 outriggers at front and rear dozer, my understanding is (and having spoken to others regarding this), both riggers and blade should be down to their full extent so they 'lock' and provide greatest stability. However, there is a lot of flexing in the blade structure during operation, and as a result the crossmember in blade linkage keeps cracking, my machine now on its 3rd, and its sister has had same part replaced only for it to break again. In fact the other machine had the original linkage from mine, repaired (and with gussets welded into the corners for additional strength), fitted, it has actually broken the strengthened version too now in exactly the same place.

Machine's owner (director of hire co. has told me to only put riggers and blade down sufficiently to take the weight, not lift machine off the floor, see how it fares then. Been doing as requested, but machine doesnt seem quite as stable at full reach. Also due to hydraulic plumbing, (feed goes to blade 1st, then 'T's off to riggers at front), blade goes down 1st, (only when it starts to take the weight does oil get forced to front), its difficult to get the wheels to remain in contact with the floor, without jiggling it up and down and/or switching blade off to allow riggers to catch up.

Would be interested to know what opinions are from others, I know there are others on here with far superior knowlege to mine, Id value your input, as much for curiositys sake as anything else. (Personally I think its down to very poor build quality of the machine. Hopefully I'll get the tracked version next time...)

Regards, Hugh.

[Robban_C]

I know what you mean. The blade on my EC35 tends to flex sideways if exposed to "uneven" surfaces and big loads sideways.
I haven´t had any cracks yet, knock on wood.

Could be an idea to replace your blade with another pair of outriggers? I know that they do that sometimes on Volvo rubber ducks if they are used on such jobs. And all the wheeled material handlers have 4 outriggers.

Could an extra counter weight be an idea?
Or extra weights in the under carriage?
The Volvo EC45 PRO has a bigger counter weight and some extra weights in the u/c on the sides compared to the older non-PRO EC45. I can get you some exploded views if you would like to. The total weight difference is 300 kg, not much but you must remember that those machines are small with total weights of 4250 kg and 4550 kg so the difference is 7%.

[Hugh Jaleak]

Ideally another pair of riggers is the way to go, but I cant see the owners spending the money to do that. Machine works sitting on a virtually level concrete floor, most of the flex comes from movement during operation, I can see how additional counter weights could assist, but again its cost involved in retro fitting them to the machine that makes it prohibitive. Sadly these machines have not exactly been free from problems (and expense) since they were new. Things have broken that just simply shouldnt have broken on a machine of that age. Cat have swallowed a lot of the cost under warranty, but now at nearly 3 years old, and 4000 hours Cat wont do it much more. Having said that, we are now getting to the stage of replacing parts that have already been replaced under warranty because they've broken again! (Blade frame being one of them!)

Personally Id have had a tracked machine from the start. It was the bosses choice to have rubber ducks, he wanted Volvo but lease company preferred the Cat. Tyres and waste dont mix, although I try and keep a mattress or 2 nearby to clean working area with, it doesnt prevent every puncture. A piece of broken glass and a wire staple have been sufficient to cause a flat before now....

[Neil D]

Sounds to me that this machine is operating dangorously with this set-up be very carefull with regard to health and safety especially your own obligations under H&S.

Cheers
Neil

[Hugh Jaleak]

I have been doing this job now for last 3 years with this machine, it seems wear has accelerated failure factor of some parts, i.e. blade. Business is now owned by a multinational company and believe me H&S is a very serious matter to them. I have no concerns with driving it, I know the machine and operate it within its limits. Hindsight has shown it would be more stable with the smaller Cat 310B grab fitted, but we only have this year to run then it will be due for replacement anyway. Hopefully, with our input as drivers more suitable machines will be selected as replacements.

As an aside my employer's have spent around the £80K mark on safety improvements since taking over last year, we currently have a guy on site from Holland wiring up extra E-stops and cut outs on the sorting plant, extra fencing and guarding has gone up just about everywhere.....

[BulldozerD11]

Hi Hugh

Sounds like they are covering themselves by using consultants to look for problems that dont exist, and ignoring the big ones. Saying its due for replacement next years no excuse for carrying n if there is issues with it. (And dealers will be looking to shift machines if trades down so a good deal may be available to swap the machine now, especially swapping makes)

Cover yourself by by reporting stability issues and fatigue cracking in writing to your boss and H&S dept, so if any thing goes wrong its not blamed on operator error. As past repair history will back it up. They should fit a smaller grab really as its not as stable as it should be if its flexing so much that stress cracks occur repeatedly. IMO. (You must be fairly concerned to have posted your thoughts on here).

The materials / waste handlers with outriggers all round sound a better idea if they must have wheeled ones. But tracks as you say would be more stable, and could fit rubber pads if on some surfaces that can damage or for crossing road ways between the concrete areas.

I would have thought that the machine and a full grab should be stable at full out reach on the jacks with a factor of safety, or fitted with a load / radius limiting system like a crane these days with the electronic controls on everthing. I was using a telescopic forklift a few years back and that wouldent let you move if the load was too much at the radius/extension of the boom. It wanted the legs down and in some cases would not let you lift them up to manouver.

Dave

[Hugh Jaleak]

Hello Dave,

Firstly thankyou for your input, I appreciate that. Our H & S is done in house, but in common with the rest of the country they think everyone's stupid and cover the slightest risk... Sadly there has been another recent fatality in the waste industry, so its no surprise everyone is looking at their site very closely at present to further minimise any risk.

As to the machine, I have to fill in a daily checklist at the start of every shift to show ive inspected the machine, and deem it safe to use. Any major defects, I am expected to report to management immediately. My main concern (and reason for initial post) is covering my backside regarding the blade. I am confident the machine wont go over, but we've had so many problems with these ducks since day 1, it has become an ongoing saga.

IMO the blade is simply not man enough to act as a stabiliser. Just moving the boom up and down in close proximity to the machine is sufficient to cause the blade to twist, once digging forces come into play then the stresses caused become capable of fracturing the structure.....

Nick.