1. #1
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    Default PTO gerenator with PTO pump

    My department is in the process of specing a new rescue that is going to have a 250-500gpm pump. We're exploring our options for on board generators. We have one company stating they cannot do a pto pump and pto generator due to the size of the pto ports and the inability to have the both running properly so he is proposing a hydraulic generator(20kw). Another mfg says that they can run both ptos but the pump (500gpm) would be limited to 300gpm while the generator(30kw) is in use. The generator will be powering a electric trimo hurst power unit, a light tower(NS10-9000), and 2 electric cord reels. The pump will be used as a protection line during extrications. Does anyone have any experience with dual PTO's? Any recommendations for generators types, brands etc.?

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    It's a bad idea to have a PTO pump and a PTO generator. The PTO will need control of the engine so if you need increased pressure on the pump, you're not going to get it while the generator is running. Go with a hydraulic generator and a PTO pump.

    I'm not sure what the application of the PTO pump is? If it's just for car fires, dumpster fires, etc then my personal preference would be to keep the PTO generator and install a UHPS pump to take care of the car fires. A UHPS system with a little foam has great firefighting capabilities.

    There are quite a few manufacturers of them out there now. Rosenbauer does make a nice one. There are a few videos on their website showing the UHPS unit in action.

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    Quote Originally Posted by UFDFF15 View Post
    My department is in the process of specing a new rescue that is going to have a 250-500gpm pump. We're exploring our options for on board generators. We have one company stating they cannot do a pto pump and pto generator due to the size of the pto ports and the inability to have the both running properly so he is proposing a hydraulic generator(20kw). Another mfg says that they can run both ptos but the pump (500gpm) would be limited to 300gpm while the generator(30kw) is in use. The generator will be powering a electric trimo hurst power unit, a light tower(NS10-9000), and 2 electric cord reels. The pump will be used as a protection line during extrications. Does anyone have any experience with dual PTO's? Any recommendations for generators types, brands etc.?
    I would consider the advices that you have received very carefully. I am puzzled by the suggestion to go to a hydraulic generator. That still needs a PTO to run the hydraulic pump.

    Anything with 2010 emissions, and some 2007 emissions have very limited space for PTOs. Some are limited to using only one PTO opening due to exhuast system obstructions. Be aware that the chassis manufacturer installs the exhaust system. No modifications are allowed except for the tailpipe.

    Would you have space for/consider a gen set powered by its own engine? Or pump?

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    If you are wanting a PTO pump then I would go with a diesel genset plumbed from the apparatus fuel tank. There are various options for mounting the genset including above the pump or in the bottom of the compartment depending on the size of the unit you would like.
    I can't believe they actually pay me to do this!!!

    One friend noted yesterday that a fire officer only carries a flashlight, sometimes prompting grumbling from firefighters who have to lug tools and hoses.
    "The old saying is you never know how heavy that flashlight can become," the friend said.
    -from a tragic story posted on firefighterclosecalls.com

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    Quote Originally Posted by chiefengineer11 View Post
    I would consider the advices that you have received very carefully. I am puzzled by the suggestion to go to a hydraulic generator. That still needs a PTO to run the hydraulic pump.

    Anything with 2010 emissions, and some 2007 emissions have very limited space for PTOs. Some are limited to using only one PTO opening due to exhuast system obstructions. Be aware that the chassis manufacturer installs the exhaust system. No modifications are allowed except for the tailpipe.

    Would you have space for/consider a gen set powered by its own engine? Or pump?

    From what i understood from the explanation, there is two PTO ports 1 large 1 small and the PTO generator and PTO pump both require the larger one, and the hydraulic generator can use the smaller port and get's full power at idle. the dealer pitching the PTO said the hydraulic requires a lot of maintenance. And the dealer pitching the hydraulic says that the PTO will wear a lot quicker due to it being under the truck with all the chemicals etc that are used on the roads in the Northeast.

    Ironsman: for some reason the chief is dead set against a diesel genset because the maintenance required. Which is quite funny because we have had one on our ladder for 8 years and have never had a single problem with it.
    Last edited by UFDFF15; 11-16-2010 at 02:21 PM.

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    Quote Originally Posted by UFDFF15 View Post
    From what i understood from the explanation, there is two PTO ports 1 large 1 small and the PTO generator and PTO pump both require the larger one, and the hydraulic generator can use the smaller port and get's full power at idle. the dealer pitching the PTO said the hydraulic requires a lot of maintenance. And the dealer pitching the hydraulic says that the PTO will wear a lot quicker due to it being under the truck with all the chemicals etc that are used on the roads in the Northeast.

    Ironsman: for some reason the chief is dead set against a diesel genset because the maintenance required. Which is quite funny because we have had one on our ladder for 8 years and have never had a single problem with it.
    If you go with any form of a vehicle engine-driven pump, then a hydraulic generator is absolutely the best option. They can run at any engine speed, so varying RPMS's of engine while pumping has no effect.

    If the salesman says the hydraulic requires a lot of maintenance, then run, don't walk, to a new salesman. He (she) is not knowledgable about hydraulic generators. A spin-on filter change once a year is about all thats necessary. Probably the closest thing to maintenance-free on our pumper.


    Comment about PTO gen is somewhat valid since a PTO generator is normally mounted to the frame rails and can pick up road debris, salts, etc. The hydraulic can be mounted almost anywhere, most common is above the pump house.

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    Is this on a custom or commercial chassis?

    I recently saw an older (1999) E-One cyclone chassis rescue that had that set-up. As I recall they said it worked fine.

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    it will be a International 4400 due to budget restraints.

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    Quote Originally Posted by UFDFF15 View Post
    From what i understood from the explanation, there is two PTO ports 1 large 1 small and the PTO generator and PTO pump both require the larger one, and the hydraulic generator can use the smaller port and get's full power at idle. the dealer pitching the PTO said the hydraulic requires a lot of maintenance. And the dealer pitching the hydraulic says that the PTO will wear a lot quicker due to it being under the truck with all the chemicals etc that are used on the roads in the Northeast.

    Ironsman: for some reason the chief is dead set against a diesel genset because the maintenance required. Which is quite funny because we have had one on our ladder for 8 years and have never had a single problem with it.
    It's not so much the presence of the ports, it's the access to them that can become an issue with the newer emissions systems.

    Hydraulic gen sets do need their maintenance, but it shouldn't present an onerous burden any more than anything else. They do take up space, and proper installation is critical.

    We are located in the northeast and have a frame mounted 20 kW direct drive gen set on our special service truck. Road salt and other chemicals have not presented any problems so far (it's a 1994 truck). I like it for its simplicity. The biggest disadvantage, and one that you will face, is that in order to produce 60 hZ AC, the engine has to run at one specific speed (1400 RPM in our case). That's incompatible with pump operations where your engine speeds are constantly changing.

    So you may want to revisit the separate engine. The maintenance on a good quality unit shouldn't be any more than for the engine that powers the vehicle, and probably could be done simultaneously.

    Conversely, I have seen many very nice pump installations utilizing an independent engine where the whole thing fit into a compartment. Or, for bigger pumps, using something like a John Deere diesel engine and mounted crosswise, taking up no more space than a mid mount pump. There, too, the maintenance would be no more than the truck's engine.

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    Our 2008 aerial has dual PTO's. One powers the aerial device and the other a 15kW Onan Genset. The fire pump is powered by the drive train.

    Transmission is a 4000 series Allison; the genset PTO is at 12 o'clock and the aerial PTO is at 8 o'clock. We've not had difficulty with operating two at once, of course when the aerial is engaged it usually in high idle mode.

    C6

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    I would go with a hydraulic generator as well. The fluctuating RPM's of the truck knock a PTO direct drive out of the running. Gas/Diesel units take up a fair amount of space, are louder, and require much more maintenance than a hydraulic unit. Hydraulic generators really only require a spin-on oil filter as maintenance, and can put out full power at idle. If the fluid turns brown, something is going on, otherwise there really isn't much else. We did a hydraulic generator comparison on our site if you're interested... otherwise just call around and check with the big three manufacturers (Smart Power, Harrison, Onan). You'll be much happier with a hydraulic.
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    Quote Originally Posted by Command6 View Post
    Our 2008 aerial has dual PTO's. One powers the aerial device and the other a 15kW Onan Genset. The fire pump is powered by the drive train.

    Transmission is a 4000 series Allison; the genset PTO is at 12 o'clock and the aerial PTO is at 8 o'clock. We've not had difficulty with operating two at once, of course when the aerial is engaged it usually in high idle mode.

    C6
    As mentioned above, the hydraulic generator can run at any speed and can compensate for the change in RPM's as the aerial ramps up and down. It's the reason why you see almost all aerials with hydraulic generators. However, when you're fire pump is in gear and the truck is at idle, you more than likely won't get your high idle when you start moving your aerial.

    It starts getting difficult when you have more than one device that requires a set engine speed. That's why you need to look at an alternative.
    1) PTO Generator (direct drive) / Separate Engine Driven Pump such as a UHPS
    2) PTO Pump / Hydraulic or Gas/Diesel engine driven generator.

    You will be very sorry if you go with a direct drive PTO generator and a PTO pump.

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    I forgot to mention, I do know that "thru-shaft" pumps are available. Meaning, you mount your PTO to the transmission, mount the thru-shaft pump for the hydraulic generator to it, and then piggyback the other pump onto it. This is pretty common practice on aerials.
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    You can get your 30kw rating from a PTO driven hydraulic generator if your builder is willing to do it. Harrison makes such a unit. Not sure on others.

    Technically, you could piggyback a single PTO for the generator hydraulic pump and the fire pump I suppose, or if access was available to the smaller port, you could drive the fire pump. If all you're looking for is a protection line you really don't need more than 300 gpm anyway, which shouldn't be that much demand on a PTO drive.

    I think the big question is access to the PTO ports on the tranmission with regards to the exhaust routing...

    Any chance of considering a split-shaft drive for your fire pump? A Waterous CL can be driven by either PTO or split shaft, and is rated at 500 gpm.
    "Share your knowledge - it's a way to achieve immortality." - Stolen from Chase Sargent's Buddy to Boss program

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    From everything I've been told, the PTO port on the officers side of the transmission (2 o'clock?) is not really usable due to exhaust pipes. So, you would have to rely on the one on the drivers side only.

    Harrison and Smart Power go up to 30kW, Onan goes up to 25kW.

    EDIT: Clean power is more important than just power. Keep this in mind to keep bulb replacement/equipment replacement to a minimum.
    Last edited by Tim1118; 11-18-2010 at 08:37 PM.
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    Why not go with a split shaft pump such as a Hale APMG? It will give you the 500gpm flow you are looking for and leave the pto open for the generator.

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    A problem that can occur when using a PTO generator with either a PTO or split-shaft pump is that when you are pumping, the generator is spinning higher than normal (most are geared to produce full power at idle), which COULD lead to problems.

    That or you'l have to gear the PTO down so that it's running at normal RPMs when the pump is running, meaning that you now have to run the truck at high RPMs just to make power.

    A hydraulic generator solves this problem, because it automagically compensates for fluctuations in vehicle RPM.

    That or you could put a stored-energy CAFS on the truck instead of a tank and pump.

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    Quick clarification... there are no PTO direct drive generators that I'm aware of that can be used at varying RPM's. They have to spin at a specific RPM to produce the correct voltage and frequency. Anyone know otherwise???

    Hydraulic generators pumps put out enough pressure at idle through redline to keep the generator spinning at the proper RPM... Smart Power also throws in a proportioning valve to further keep the frequency right at 60Hz.

    Gas/Diesel units operate at a fixed RPM. Pretty self-explanitory on this one.
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    Quote Originally Posted by UFDFF15 View Post
    From what i understood from the explanation, there is two PTO ports 1 large 1 small and the PTO generator and PTO pump both require the larger one, and the hydraulic generator can use the smaller port and get's full power at idle. the dealer pitching the PTO said the hydraulic requires a lot of maintenance. And the dealer pitching the hydraulic says that the PTO will wear a lot quicker due to it being under the truck with all the chemicals etc that are used on the roads in the Northeast.

    Ironsman: for some reason the chief is dead set against a diesel genset because the maintenance required. Which is quite funny because we have had one on our ladder for 8 years and have never had a single problem with it.
    I can speak for hydraulic generators as all of the newer apparatus Dalton ordered had them. Maintenance was minimal on them, we had to change the fluid once a year, or as needed but it was rarely needed. Other than that, we checked fluid levels every morning and checked the color of the fluid through the level sight. Our hydraulic gen's worked great. Be careful what manufacturers tell you, they'll say anything to sell wht they're marketing.

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    Yes, do be careful... you want to listen to what they tell you, but also do your own homework. There are a lot of things available for the fire service today that make life easier on everyone, but many don't even look at them because they feel that everything is a sales pitch. If you do your own research, you'll come out alright in the end.
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    Quote Originally Posted by Tim1118 View Post
    Quick clarification... there are no PTO direct drive generators that I'm aware of that can be used at varying RPM's. They have to spin at a specific RPM to produce the correct voltage and frequency. Anyone know otherwise???

    Hydraulic generators pumps put out enough pressure at idle through redline to keep the generator spinning at the proper RPM... Smart Power also throws in a proportioning valve to further keep the frequency right at 60Hz.

    Gas/Diesel units operate at a fixed RPM. Pretty self-explanitory on this one.
    Ravens Technology currently makes 5 kW and 7 kW direct drive unit utilizing some unique technology to produce 60 hZ at pretty much any prime mover speed. They can be PTO or belt driven. At present, 7 kW is as high as they go. I know they had a 15 kW unit on the drawing board, but I don't think they have any near term plan to bring it to market.

    The drawback of the technology is that it is sensitive to inductive loads. So if you want to use the power to operate motors (fans, for example), you would have to actually try them on one of their units to see if it would function properly.

    When I spoke with them they were very open about what they could and could not do. If your needs are primarily for lighting, they might have something for you. But then, DC works for most lighting also.

    Their web site provides a lot of good info, including explaining the technology. www.raventechpower.com.

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    I would have to agree with others here, hydraulic generators in my experience have been very reliable and virtually maintenance free. We have 2 pumpers with 8kw Harrison's. We have also experienced a pto driven generator on a '96 International recue which we experiences a few problems.

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