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Thread: Pump Gear & Generator

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    Default Pump Gear & Generator

    Is the PTO for Hydraulic Generator anyway tied into pump? Say I was to run my hydraulic generator, so I have activated my pto switch, then activated generator, have some spot lights running off the generator, if my engine is required for pumping, do I have to turn off generator before putting the pump in gear? I apologize if this question is a basic one, as im still learning all there is to know about being a great pump operator


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    Quote Originally Posted by darook View Post
    Is the PTO for Hydraulic Generator anyway tied into pump? Say I was to run my hydraulic generator, so I have activated my pto switch, then activated generator, have some spot lights running off the generator, if my engine is required for pumping, do I have to turn off generator before putting the pump in gear? I apologize if this question is a basic one, as im still learning all there is to know about being a great pump operator
    It depends on the set up of your truck, age transmission etc.... but usually no.

    Mid-ship pumps use the full power of the drivetrain by way of a transfer case. The pto is off the transmission only. There may be limits on what RPM you can engage or disengage the pto. But normally if you have the pto engaged, you can then engage the pump afterwards.

    Over simplified but not knowing specifics of your vehicle it has to be.

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    ChiefDog is right.

    There is a huge difference between running a pto and running a pump off of the transfer case. As long as you are inside the rpm limits of the pto when engaging/disengaging, it will not effect the pump. As well, you might notice a slightly higher rpm when you are trying to pump water. With the pto engaged, the parasitic load of the generator will take away, or add about 200-300 rpms to the pump to get the desired discharge pressure. Of which, most engines and tranny's can handle.

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    First you need to know if your transmission has PTO case, you can check this by looking at the driver's side, there will be a cover with 6 bolts in front of the linkage change. If it is covering, you can install anything that may be required PTO, if no coverage, you need a new transmission with the option of PTO and some internal parts to operate the PTO, or the installed on the front of the engine.

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    Quote Originally Posted by martinnman View Post
    First you need to know if your transmission has PTO case, you can check this by looking at the driver's side, there will be a cover with 6 bolts in front of the linkage change. If it is covering, you can install anything that may be required PTO, if no coverage, you need a new transmission with the option of PTO and some internal parts to operate the PTO, or the installed on the front of the engine.
    Slightly inaccurate info. Many transmissions have PTO "ports" on all sides of the transmission. They are usually referred to by "clock" positions ( 3 oclock, 6 oclock.......)
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    We always engage the PTO for the generator prior to putting the pump in gear, if needed, due to low PRMs needed when engaging the PTO and the possibilty of higher ones when pumping.

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    darook,

    You have a good question but these gentlemen have given you the right answer. I'm not as mechanically inclined as some who have answered your question but I can answer from the pump operators perspective.

    We have three apparatus currently (with a fourth on the way) that have hydraulic generators. All apparatus were built by different builders but operate the same way. You engage the PTO and shift the transfer case to Pump while at idle and get on the pump panel.

    As previously stated the generator does not require significant horse power or RPM's to operate. It basically can function at idle speeds. Conversely, throttling up the pump doesn't mess with the operation of the generator.

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    darook: I notice that you mentioned "Hydraulic" generator. Depending upon brand and control system, a hydraulically driven generator is controlled by the amount and pressure of the hydraulic fluid coming from the PTO pump and entering the hydraulic motor of the generator. Some of the newer models use the 60 cycle signal from the generator to adjust the input fluid flow to the hydraulic motor that is driving the generator. With this type of arrangement, it is necessary to "condition" (warm) the fluid to operating temperature before applying an electrical load to the system. There might be a restriction on the sequence needed to start the system, like beginning the operation with no load on the generator until the 60 cycles is achieved. We have two such systems, one on the quint and another on the heavy rescue. SOP on both is to leave the main breaker in the OFF position, so that the generator always starts under a no-load condition. By the time the driver puts all the PTO's and Main pump in gear, the hydraulic system has had enough time to stabilize at 60 cycles. When operating without the fire-pump, the high idle switch takes the motor to about 1200 RPM and holds it there to operate the aerial hydraulics and the generator, or in the case of the rescue, it correctly powers the Amcus tools. When the fire pump is put in gear, it automatically disables the high idle setting, because the pump pressure and volume get operating priority.

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    Some PTO generators are constantly engaged, turning them only diverts the hydraulic fluid. You can shift these anytime you want. Idle, 55 mph, or 1,500 GPM.

    Some older units on 4-speed Allisons might be turbine driven, so you'll need a hot shift or put the truck in drive+road gear to shift it.

    If you've got an Allison world transmission, then it's flywheel driven, and all of those require a hot shift. Just bring the enine RPM's below 1,000 and it should be safe to shift.
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    Sorry, Mr. Fleming. A conductor passing through a magnetic field DOES NOT induce a voltage. It creates a current. Said current when applied to a resistance causes a proportional voltage. If the conductor is open circuited, the voltage will rise until an arc is created between the opposite ends of the conductor. This might be a very significant voltage depending upon the insulation of the wire and the separation distance between the opposite ends of the conductor. A second problem occurs when the magnetic field, created by the current collapses and induces a back flow of current causing the voltage to reverse polarity.
    slackjawedyokel likes this.

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