Increasing input HP to gearbox.
Increasing input HP to gearbox.
(OP)
Hi all. I'm hoping someone here can give me some guidance as I don't have a lot of experiencein working with gearboxes.
I have a 750:1 gearbox being driven by a 1HP motor connected to a VSD. The input HP as defined by the data tag is 1.38 HP. The motor runs at 10 Hz raising the load until it reaches its destination, but the drives faults out on overcurrent before the load reaches its destination. Can I safely replace the 1 HP motor and drive with a 2 HP motor and drive without damaging the gearbox? If this isn't an option, would changing the sprocket sizes to allow the motor to run a more optimum speed help?
I have a 750:1 gearbox being driven by a 1HP motor connected to a VSD. The input HP as defined by the data tag is 1.38 HP. The motor runs at 10 Hz raising the load until it reaches its destination, but the drives faults out on overcurrent before the load reaches its destination. Can I safely replace the 1 HP motor and drive with a 2 HP motor and drive without damaging the gearbox? If this isn't an option, would changing the sprocket sizes to allow the motor to run a more optimum speed help?





RE: Increasing input HP to gearbox.
You should not exceed the power rating of your gearbox. At the very least, chat with the gearbox manufacturer and see what they think.
If you can change sprockets to increase your total gear ratio, you reduce your power. That ought to solve your problem. Your speed will be reduced accordingly.
You should take a close look at the overall design, and chat with the original designer if necessary. I am not aware of any safety issues with overloaded gearboxes. Your gearbox may have been correctly sized for half your load. If anything else was correctly sized for half the load, you have a safety problem.
JHG
RE: Increasing input HP to gearbox.
RE: Increasing input HP to gearbox.
RE: Increasing input HP to gearbox.
You could put a 300hp motor on the input and as long as your output only requires 1hp, that's all the motor, or the gearbox, will ever see.
If you're faulting out your motor, then your load is probably greater than its 1.0hp rating. If you go to a 2hp motor the gearbox may or may not see all 2.0 hp. It's possible that the load is somewhere between 1hp and the 1.38hp rating of the gearbox, but if it's closer to 2hp, then you're going to overload your gear train. Even if it falls in the gearbox's range, your probably pushing the envelope.
You need to determine what your ouput power requirements are, then divide by the efficiency of the gearbox and include a safety factor.
Don
Kansas City
RE: Increasing input HP to gearbox.
If you increase the motor speed at a given torque, you are increasing the power and making your problem worse. Power is force×velocity and torque×rotation speed.
You did not say what kind of motor you have. If it is a DC motor, your maximum torque is at stall, your maximum power is at half of no-load speed, and your maximum efficiency is somewhere in the vicinity of 2/3 no-load speed. Your torque is approximately a function of current, and your voltage is approximately a function of motor speed.
If it is not DC, the following remarks are less correct, but still pretty valid.
If you were to double your gear ratio and run the motor twice as fast, you would be producing the same power at very approximately half the torque. The gearbox efficiency would affect this. Your current goes way down. This might solve your problem without affecting speed.
You really should talk to the original designer. You should not modify bits and pieces of a system if you do not completely understand how it works.
JHG
RE: Increasing input HP to gearbox.
I was hoping for a simple, less costly solution to this problem, but that hope is fading fast. Again, thanks for the replies.