943 BOBCAT

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hawg wild

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May 8, 2006
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I am still looking around at some skidsteers here locally and came across a 943 bobcat the other day. this thing is huge. I looked up the specs on this machine and found that it is only 75 hp. for the size of this machine it looked like it should have more hp. 2400lb lift cap. 24gpm flow and 2100psi. Anyone ever had any experience with this particlar model? This machine had two hydradulic cylinders mounted on either side of the back of the machine they were attached to a bar that ran across the back of the width of the machine. what was this for? what type of motor does this machine have? Is it a duetz? how about the psi rating. some of the attachments that i am interested in (brushwolf or brushcat and a tree shear for example) call for a minimum psi rating that is higher than 2100psi. How does this come into play? the machine meets the flow requirements but is not rated high enough in the psi category. will this machine run these attachments? this looked like a big stable machine, but if it won't run the attachments that i want then i don't need it.
 

Tazza

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Its not so much the pressure, its the flow you need. You will need to see what flow the machine will produce and what flow your attachments require. You will require as much pressure as possible for a tree shear though. The more pressure you have, the larger trees you can shear.
The 2 cylinders on the back were rear stabilizers, you use them with a backhoe attachment so you can apply more downward force on the attachment, it will also help prevent the machine from moving while digging.
75HP is quite alot, don't forget the machine may look big and mean, but it doesn't have to move very fast. Slow but powerfull.
 

Eric

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Jan 19, 2005
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169
Its not so much the pressure, its the flow you need. You will need to see what flow the machine will produce and what flow your attachments require. You will require as much pressure as possible for a tree shear though. The more pressure you have, the larger trees you can shear.
The 2 cylinders on the back were rear stabilizers, you use them with a backhoe attachment so you can apply more downward force on the attachment, it will also help prevent the machine from moving while digging.
75HP is quite alot, don't forget the machine may look big and mean, but it doesn't have to move very fast. Slow but powerfull.
I believe the bar in the back may also be used as a scarifier/rippers if you install shanks on the bar.
 

hawg wild

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May 8, 2006
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I believe the bar in the back may also be used as a scarifier/rippers if you install shanks on the bar.
I asked what year model the machine was, but they did not know. 94 was the last year the made the 943. It has 1251 hours on it, and they are asking $14500.00 with a bucket and forks. I know this is a big machine and all, but that seems a little high. What do yall think?
 

skidsteer.ca

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Jan 20, 2006
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3,853
Hawg
The 75 hp is a little low by todays standards but still quite capable. remember with a skidsteer in the situations where you begin to run out of power it is vary easy to slow your ground speed until the engine recovers. The situations where you run short would be ie, running a brusher in thick growth and climbing a steep hill at moderate to fast speeds. Both your hydros (drives) and front quick couplers would be putting a heavy demand on the engine. In this case you would drop your speed to what the engine can manage. Would 100hp be better. Of course, but it will need more fuel, and it will only be better in the situations where you can use high wheel speed.
As for the pressure and flow. Flow is what dictates your brusher rpm, the more flow the less engine rpm needed to run your cutter the necessary speed, or the faster you can spin your cutter at max throttle. Most cutters need to spin in a certain rpm range, so the size of the motor (on the cutter) needs to match the volume of the pump on the machine. remember you can always vary the volume down some by reducing engine rpm. I believe that volumes measurements are taken at full rpm.
Pressure on the other hand is what tries to keep everything spinning. Say you engage the oil to your brusher and it starts to turn. The pressure in the lines will be high until the brusher rpm gets up to the speed that matches the loader engine speed. Then the pressure tapers off and may only be 150 psi. You slam the throttle open and the pressure spikes to max relief valve setting (say 2100psi) again until the cutter catches up, then it tapers off. So you got to work, mowing light brush and the pressure varys between 150 (no drag/load on cutter) to say 1000psi because you are only cutting 3 or 4 sapplings per foot of travel, the momentum (flywheel effect of the rotating parts) of the cutter is whats hacking off the brush and the 1000 psi is enough to bring the cutter rpm back equal to the engine speed in between sapplings.
Now you move into some heavy brush and after wacking down a few sappling all at once, your momentum is used up, the cutter begins to slow, as a result your pressure climbs to max (2100) at this point, the maximum engine hp the cutter can draw is being used. and the maximum hp the hydraulic drive can produce is being created. (there are hydraulic formulas you can use to calc how much hp it takes to produce 24 gpm at 2100 psi) and you would know how much of you 75 is left for the wheels.)
However the reality of brush mowing is you wack a tree/brush at you pressure hits relief instantly, (the full hp you can create is going into the cutter) and the cutter usually makes the cut, but losses alot of momentum, then in the next few seconds it recovers its momentum just in time to be ready for the next tree. The more engine you have, and the more pump and hyd motor volume (flow) and pressure you have the faster your momentum (cutter speed) will recover, and the faster you can cover ground. So how fast do you want to go? How much do you want to spend? Only you can answer that.
I have mowed brush with a 753 up to 3“ with 13gpm and 2500 psi.
Then I stepped up to a 773, it puts out 17 gpm and 3000 psi. I resized my brusher motor to run the same 540 rpm into the brusher gear box, but now I have more torque, 56% more. Did it help much, yes and no. In moderate even loads it does, but when I whack a heavy clump, it still stops or greatly slows the cutter, and I still wait.
And that is the curse and the bonus of hyd drive, Because it is better to wait a few seconds then it is to have every ounce of the engines energy tear the guts out of the gear box.
The tree shear now is a different story, that one is all pressure, (there is no momentum) the flow just opens and closes the jaws at X speed, the psi is what “gets er dun“
Ken
 

Dwan

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Joined
Jun 1, 2006
Messages
8
Hawg
The 75 hp is a little low by todays standards but still quite capable. remember with a skidsteer in the situations where you begin to run out of power it is vary easy to slow your ground speed until the engine recovers. The situations where you run short would be ie, running a brusher in thick growth and climbing a steep hill at moderate to fast speeds. Both your hydros (drives) and front quick couplers would be putting a heavy demand on the engine. In this case you would drop your speed to what the engine can manage. Would 100hp be better. Of course, but it will need more fuel, and it will only be better in the situations where you can use high wheel speed.
As for the pressure and flow. Flow is what dictates your brusher rpm, the more flow the less engine rpm needed to run your cutter the necessary speed, or the faster you can spin your cutter at max throttle. Most cutters need to spin in a certain rpm range, so the size of the motor (on the cutter) needs to match the volume of the pump on the machine. remember you can always vary the volume down some by reducing engine rpm. I believe that volumes measurements are taken at full rpm.
Pressure on the other hand is what tries to keep everything spinning. Say you engage the oil to your brusher and it starts to turn. The pressure in the lines will be high until the brusher rpm gets up to the speed that matches the loader engine speed. Then the pressure tapers off and may only be 150 psi. You slam the throttle open and the pressure spikes to max relief valve setting (say 2100psi) again until the cutter catches up, then it tapers off. So you got to work, mowing light brush and the pressure varys between 150 (no drag/load on cutter) to say 1000psi because you are only cutting 3 or 4 sapplings per foot of travel, the momentum (flywheel effect of the rotating parts) of the cutter is whats hacking off the brush and the 1000 psi is enough to bring the cutter rpm back equal to the engine speed in between sapplings.
Now you move into some heavy brush and after wacking down a few sappling all at once, your momentum is used up, the cutter begins to slow, as a result your pressure climbs to max (2100) at this point, the maximum engine hp the cutter can draw is being used. and the maximum hp the hydraulic drive can produce is being created. (there are hydraulic formulas you can use to calc how much hp it takes to produce 24 gpm at 2100 psi) and you would know how much of you 75 is left for the wheels.)
However the reality of brush mowing is you wack a tree/brush at you pressure hits relief instantly, (the full hp you can create is going into the cutter) and the cutter usually makes the cut, but losses alot of momentum, then in the next few seconds it recovers its momentum just in time to be ready for the next tree. The more engine you have, and the more pump and hyd motor volume (flow) and pressure you have the faster your momentum (cutter speed) will recover, and the faster you can cover ground. So how fast do you want to go? How much do you want to spend? Only you can answer that.
I have mowed brush with a 753 up to 3“ with 13gpm and 2500 psi.
Then I stepped up to a 773, it puts out 17 gpm and 3000 psi. I resized my brusher motor to run the same 540 rpm into the brusher gear box, but now I have more torque, 56% more. Did it help much, yes and no. In moderate even loads it does, but when I whack a heavy clump, it still stops or greatly slows the cutter, and I still wait.
And that is the curse and the bonus of hyd drive, Because it is better to wait a few seconds then it is to have every ounce of the engines energy tear the guts out of the gear box.
The tree shear now is a different story, that one is all pressure, (there is no momentum) the flow just opens and closes the jaws at X speed, the psi is what “gets er dun“
Ken
943 used a perkins for power. There quick atch is different size then the smaller brothers (700 - 800 series) and smaller then the big bobcats like the 974/975/980 series. That asking price is a tad high. I would think you should be able to find one for around $9K in good condition. If a large machine is what you are looking for there are a few of the bobcats on steroids still around. (3700 lb. working load /7400 lb. tiping) I found one last summer for $6500 and was offered another one in good condition for $9K this spring. 975 has 2200 psi at 31 gpm in high flow and 11 gpm on low flow. they weigh in at 12000 lb give or take. The 974 had the same perkins as the 943 and the one I have has never let me down. it is a little low on power when pushing a snow pusher over 14' wide full of wet snow w/chains but that is about the only time I have noticed it lug down. the 975 came with a John Deer @85 hp and is noticable as it is smother to run. I did a replacement motor in one about 12 years ago and went with a 125hp turbo JD. The added HP rased havic on the sunstrand pumps after 10 years and an aditional 5000 hours. What ever you do do not buy replacement pumps or motors from Bobbcat. the price will be more then the machine costs. Dwan
 

bobbie-g

Well-known member
Joined
Mar 15, 2004
Messages
576
943 used a perkins for power. There quick atch is different size then the smaller brothers (700 - 800 series) and smaller then the big bobcats like the 974/975/980 series. That asking price is a tad high. I would think you should be able to find one for around $9K in good condition. If a large machine is what you are looking for there are a few of the bobcats on steroids still around. (3700 lb. working load /7400 lb. tiping) I found one last summer for $6500 and was offered another one in good condition for $9K this spring. 975 has 2200 psi at 31 gpm in high flow and 11 gpm on low flow. they weigh in at 12000 lb give or take. The 974 had the same perkins as the 943 and the one I have has never let me down. it is a little low on power when pushing a snow pusher over 14' wide full of wet snow w/chains but that is about the only time I have noticed it lug down. the 975 came with a John Deer @85 hp and is noticable as it is smother to run. I did a replacement motor in one about 12 years ago and went with a 125hp turbo JD. The added HP rased havic on the sunstrand pumps after 10 years and an aditional 5000 hours. What ever you do do not buy replacement pumps or motors from Bobbcat. the price will be more then the machine costs. Dwan
Dwan, where do we go to get quality pumps or motors other than Bobcat? I agree, they really sell high, but I don't know what the alternatives are. ---Tnx, Bob
 

Dwan

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Joined
Jun 1, 2006
Messages
8
Dwan, where do we go to get quality pumps or motors other than Bobcat? I agree, they really sell high, but I don't know what the alternatives are. ---Tnx, Bob
I have found a few Hydrostatic Rebuilding shops on line that will rebuild sunstrand pumps and motors for 1/10 the price of new from bobcat. Most have been in the south east. I got a cataog in the mail that may help. will check on it tomarrow. Dwan
 

sterlclan

Well-known member
Joined
May 1, 2004
Messages
528
I have found a few Hydrostatic Rebuilding shops on line that will rebuild sunstrand pumps and motors for 1/10 the price of new from bobcat. Most have been in the south east. I got a cataog in the mail that may help. will check on it tomarrow. Dwan
Precision fluid power 405-239-7767 fax 405-235-1682 www.pfpl.com the salesman/tech I delt with is Patrick Morgan email [email protected] he was very helpful new pump less than half the cost at bobcat Jeff
 
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