OK so I don't know what this option is used for. I looked in the operator's Manual and it said its used for moving material long distances to help with driver fatigue which I understand. But we have a operator here who sets it to max rpm and runs the loader all day long with the rabbit mode on. So he digging with it sitting over the rock crusher dumping his load with it on. So my question is what is the intended purpose of the rabbit mode can you keep it on and dig with it on. And what does cat consider long distances to have it on? And I want to have the right answers defore i go tell him hes doing something wrong because it just seams like the operator is just tearing up the machine. Thank you
Are you referring to the Throttle Lock control that enables you to set the engine at any particular RPM and run the machine just using the left (neutralizer) pedal to control ground speed and while making direction changes..? There are 2 switches one behind the other located on the RH console just to the right of the bucket lift & tilt controls.
Yes the throttle lock controls it has a rabbit icon when turned on so that's what I call it haha
We know it by that name as well. Here's the deal as I see it. All large-ish loaders work better when the engine is at full RPM because cooling systems are at full flow, hydraulics at max flow, etc, generally the machine is more efficient. I know the Operation Manual says "Use the throttle lock control on long hauls in order to avoid driver fatigue" but I'd use it all the time TBH. I always would recommend setting the Throttle Lock with the RPM at maximum (or almost maximum if the operator was not comfortable running the machine 100% flat out for reasons of a tight space or similar) and running the machine just on the left pedal. When you press the left pedal the first few degrees of movement reduce the drive in the torque converter, the next apply the brakes. If there is any occasion where you don't need full RPM (like dumping into a hopper if you are going to be stationary for say 10 seconds or more) a touch of the RH brake pedal will deactivate the Throttle Lock and drop the engine RPM to Low Idle at which point the loader can be run on the throttle pedal with the right foot then simply press the Resume Switch on the Throttle Lock when you're ready and go straight back to the RPM that was previously set with the Throttle Lock. For truck loading I'd always recommend to run the machine on max RPM with the Throttle Lock, other types of operation may differ a bit. Either way running on the Throttle Lock just using your left foot is not doing the machine any harm.
Nige, That is a good explanation. I posted a question about it on the "Caterpillar On-line community" a very under used forum, back in 2013 and never got one reply. This site is many times better, have a question and many times in a matter of minutes someone will respond. Seams with all the effort Cat went through to design and install this system on the loaders someone could have spent a few minutes explaining it in the operators manual. Only problem with doing this I know many bosses who would freak out if they heard some one loading trucks with engine staying near full RPM. Just like in the days before full automatic shift haul trucks, the ones with manual shifted Allisons, it was almost impossible to convince some that the term "Powershift" meant just that! The WA600 Komatsu we have, or should I say they have were I used to work, had a very low tech version of this. It has a little toggle switch to the left of the steering wheel. When in the on position it activates a small air cylinder that pops out and pushes the throttle linkage enough to raise low idle speed a few hundred RPM.
One other thing worth commenting on while we're on the subject of Cat Large Wheel Loaders is how the engine RPM drops when the machine is digging. I've lost count of the number of operators I've had complain that their engine was "down on power" when in actual fact they were getting more torque. The system worked on the basis of reducing engine speed to max. torque RPM when the machine was loading the bucket, determined by 3 factors - transmission in 1st forward, ground speed less than 1mph, and bucket below a certain height. When you hear the machine doing it you could swear it's lacking power but in actual fact it's producing as much torque as it possibly can, and that torque is what will turn the hydraulic pumps and drive the converter to load the bucket.
I think the application is what would decide when and how to use the throttle lock system. I've seen many a gravel pit doing mixed loading with load and carry and having different results on the fuel usage. Loading highway trucks out of a stock pile we saw that being run wide open throttle used more fuel per day because of slight changes in when trucks pulled in. It didn't take much to go from 25 seconds between loads to maybe one truck driver being drifty and not paying attention and take a minute or more to pull under the bucket. The loader used more fuel running full out then than one who ran on the peddle. On the other hand a 988 loading 773 haul trucks working a pit face staying full throttle all day long did better on fuel than the operator running on the peddle. The biggest issue was finding that operator who felt comfortable with the engine screaming loud, riding the brake peddle all day long and staying in control of the machine. A slight miscue or slip off the pedal when dropping a load into a truck or hopper might bring about a disaster many times more expensive than the fuel used or production increase. I agree with Nige that it shouldn't make any difference in how long the machine lasts given a competent operator. I have worked with some very good operators running 988B machines that ran with their foot on the floor using the left peddle and never loosing control of the machine. The operator could drop his foot off the peddle at any hint of an issue.