New to me Cat 973 - is it working correctly?

[Reubenrr]

Ahh, striker bars. I didn’t know what they were called - thanks cm1995.

Are they strong enough to stop the vehicle if you run into something in reverse?

 

[Nige]

Ahh, striker bars. I didn’t know what they were called - thanks cm1995.

Are they strong enough to stop the vehicle if you run into something in reverse?

i suppose the answer to that question is - it depends how fast you're going........

They are not part of the 121-3969 Modification Arrgt, and neither do they appear in either the regular Parts Manual or the Custom Parts Manual for the 86G machine. Certainly the frame for your machine as shown in the Parts Manual has the attachment points for them.

 

[Reubenrr]

Haha, I suppose it does. I guess for a landfill it may be more about pushing the obstacle out of the way since it’s literally a pile of junk you’re driving through.

So even more a mash-up of parts!

 

[Nige]

I suspect the striker bars are likely OEM, I just can’t find them in the Parts Manual. I was also somewhat surprised that I couldn’t find them in the as-built arrangement.

 

[Cmark]

The term "striker bar" in Caterpillar world refers to "striking" material from the tracks before it can get jammed under the fenders, not Bubba striking other things through not looking where he is going.

 

[Nige]

The term "striker bar" in Caterpillar world refers to "striking" material from the tracks before it can get jammed under the fenders, not Bubba striking other things through not looking where he is going.

That's what the fcukoff great bumper bolted on the back of the chassis is for.....

 

[Reubenrr]

That makes more sense, Cmark. It would be hard to make those strong enough to make up for my stupidity sometimes

 

[ippielb]

Here's a couple videos of my 973c to compare the sounds you hear.

Mine is a newer model so it may vary hydraulically. But yes, the hydraulic whine is common. It's the nature of the beast.

As for spinning the tracks, you can slow the tracks/engine with load. Best practice when that happens is to slow your travel speed, if you know you're going to be in for a big load. with the travel lever half way it will slow the machine and load the engine. But if you compensate for the expected load by putting it 1/4 of the way, it will keep your engine revs and you'll actually be able to push through without spinning the tracks.

You'll learn with more seat time some tricks.

Also, if you're lifting the loader arms you cannot curl the bucket up to scoop at the same time. The lift function has priority.

 

[Reubenrr]

Ippielb, thanks for the driving tips. I’m definitely in need of some learning. Good to know the hydraulic priority on the lift vs curl. I’ll try to be sure I change the speed with load as you suggest.

It looks like your machine maintains speed when you steer. Mine doesn’t and is quite a bit louder when I turn than when going straight. Yours sounds pretty similar when going straight or turning, but maybe that’s just the video.

The photo tach showed up last night. I’ll try to get measurements during kiddo nap time today.

 

[Cmark]

Don't get too hung up on the difference between your machine and ippielb's video. His machine is a whole generation newer than yours and apart from both being hydrostatic, the drive systems are totally different.

 

[Reubenrr]

Ok, got the photo tach out and tested the machine. Idle is about 715 rpm, throttle just befor shot off. The notch at the fast end of the throttle is wider than the lever, so here it is at both ends:
2365-69 front of notch
2376-78 back of notch.

Looks like it’s at the very high end of what Cmark recommended.

I’m not really sure I could measure loaded rpm with the photo tach since I have to stand on the striker bar to get the measurement off the flywheel on the back of the crankshaft. Is there a better way to get the measurement with a photo tach?
Thanks,
Reuben

 

[Cmark]

I’m not really sure I could measure loaded rpm with the photo tach since I have to stand on the striker bar to get the measurement off the flywheel on the back of the crankshaft. Is there a better way to get the measurement with a photo tach?
Thanks,
Reuben

Good question. If your phototach doesn't have some kind of remote sensing capability you may have to get creative. Just some suggestions;

Rig up something with zip ties and tape so the tach can work while you drive the machine? Does it have a min/max hold feature?
As above but rig your phone to video the tach screen?
Take it apart and extend the wires to the sensor?

 

[Reubenrr]

I drove it a bit after taking the rpm measurements, and I did notice that it steered pretty strong when I first started, then slowed as I worked it more. The noise seemed a bit louder after it warmed up, too. This is also the coldest I’ve used it, about 35F out. The other two times it was in the low 60s to start with.

Cmark, I’ll fiddle with the tach a bit and see what I can do.

Cheers,
Reuben

 

[ippielb]

I’d just buy a magnetic trigger tach, all you need to do is put a little magnet on your balancer(glue it on), then make a bracket to put the magnetic trigger within the right proximity. Run the tach wires into the cab. Self contained I’m sure you can find them on Amazon.

“Proximity tach” I believe they’re called

 

[Reubenrr]

So, after fiddling with some of the proposed options to get rpm while moving, I remembered an app I ran across called “Engine RPM”. It uses the sounnd to determine rpm. I tested it on an old truck last night and it worked quite well, so gave it a shot on the 973 this afternoon. It ended up working, but only with the cab door open - I guess some of the sound insulation is still working

the rpm at full forward speed varies from 1940 to 1990 rpm. This was over a field, so not perfectly smooth by any means.
Cheers,
Reuben

 

[Reubenrr]

Hi All,
A couple of updates. I got my service manual in the mail last week and have been reading about how the system is supposed to work. I got through the seven systems, but can't say I really understand it all yet. Need to read through it again.

From the service manual I followed the procedure to adjust the steering linkage. That eliminated the play or free travel in the pedals, so it feels better to drive now. Unfortunately I dropped a 9/16" wrench down in the belly pan in the process. I'll need to drop the back access plate at some point to see if I can find it.

I did drive the machine some more last week and tried to pay more attention to exactly how it was behaving. A few things to note.
1. The steering always starts strong, then fades. Not really so much with being warm or cold fluid, but the start of each turn is stong, then it fades. So when I push a steer pedal, it turns strongly at first, then slows way down as I keep the pedal depressed. It feels like there is not enough flow rate to sustain the higher rate when turning.

2. Lifting the loader arms when heavily loaded slows the engine RPM significantly. The engine doesn't stall, so something seems to be bypassing eventually, but the engine really slows down. I didn't have the RPM app running so didn't get a reading of it, but i sounded slow enough I was worried the engine would stall. All the other hydraulic functons don't do that (tracking straight, or curling bucket). I am digging into an old railroad grade, and know that the arm lift is the weakest, so it may just be too much for the machine.

So, the question for those with more experience than I: it seems like I have insufficient flow to support turning, it seems like this is a flow problem or leak problem in the system. Is the best thing to do next a hydraulic pressure test? I did order a new filter, but the one I received wasn't a Cat brand and when I looked up the part number it didn't cross to any of the Cat numbers, though I'm a bit uncertain what the correct filter number is. The Cat site when I used it had several options, and they changed when I looked it up a second time?!?

Thanks,
Reuben

 

[Cmark]

At the risk of repeating myself, engine RPM is the key. If the transmission won't pull the engine down past 1850 RPM then that suggests the underspeed system is working OK.
If the implements will bog the engine down significantly, I would suspect a lack of engine power. Looking back at your first post, your fuel filter has 300 hrs on it, correct? Start with changing that and also check the air filters. Next easy test is for fuel transfer pressure. There should be a port in the fuel filter head that you can plug a gauge into.

 

[Nige]

At the risk of repeating myself, engine RPM is the key. If the transmission won't pull the engine down past 1850 RPM then that suggests the underspeed system is working OK.
If the implements will bog the engine down significantly, I would suspect a lack of engine power. Looking back at your first post, your fuel filter has 300 hrs on it, correct? Start with changing that and also check the air filters. Next easy test is for fuel transfer pressure. There should be a port in the fuel filter head that you can plug a gauge into.

I would also suggest that you find the drain tap for the fuel tank, open it and let it run a bit. See what comes out in the way of water and sediment. It probably hasn't been opened in years.

Once you have sorted out your fuel system as suggested by my learned friend above, here are the details of your hydraulic tank filter elements.
Element - 2 x 1R-0722
O-ring seal for cover - 2 x 5H-6733[/QUOTE]

 

[Reubenrr]

Hi All,
Sorry for the radio silence - my day job and the weather have conspired to keep me away from the machine for a while. I bought new fuel filters and changed them both (spin on, and cartridge) today. Both were filthy!! Unfortunately, a test drive after changing them had no effect on loss of power when loaded.

On a related note, I could not find a Cat replacement for the cartridge style fuel filter, only a NAPA part - 3360. That was the part in there when I replaced it. I noticed that the maintenance manual says to clean the cartridge filter - was it originally a screen or some other type of filter?

Unfortunately I ran out of time to test fuel pressure. I did see a plug on the head of the spin on filter mount, is that the location you were referring to, Cmark? What should the pressure be?

Thanks,
Reuben

 

[Reubenrr]

I also took a video of driving the machine so you can see if me saying it’s losing power is reasonable, or if I’m just crazy. I used the audio RPM meter for about 5min while operating and despite sounding to me like the engine was really bogging down, the RPM never dropped below ~1900. So it does seem that the underspeed cutoff is working correctly.

As far as draining the tank, I can’t find access to the bottom of the tank except for through a very large plate on the bottom of the machine. The manual says it weighs about 200lbs, so I didn’t try to remove it since the machine is in a field. Am I missing an access point for the tank drain?

Thanks
Reuben