Reverse ratchet

[abuzent]

Hello all,

I am doing these bid evaluations and was wondering how does a reverse ratchet work and its configuration. It is for a motor that drives a vertical turbine pump for river intake system

Thanks

abuzent

 

[abuzent]

Do I even need a Non-reverse ratchet.. two bidders offered one and two didnt. I know the pumps will be on continuously for 24/365 for 15 years (except maintenance), taking water from the river and pumping it to a processing plant

Thanks

 

[chestilow]

This website might give you some idea of the non-reverse ratchet.

http://www.usmotors.com/Products/ProFacts/1-307.htm

Basically, in vertical pumps when pump stops the water will flow backwards. This will result in the pump/motor rotating backwards. If the pump were to trip and go into this condition and then an operator tried to start it up, damage to the pump/motor could occur. Not knowing your piping configuration (i.e. if there are check valves on the pump discharge), I'm not sure if it would be a necessity or not. I don't know what horsepower you're dealing with, but I can't imagine the option is that much of a cost adder for the insurance it offers. At the least you might contact the vendors that didn't offer it and ask them to give you the option. I personally would recommend purchasing the option.

 

[rmw]

If you have adequate check valving that will prevent an adjacent pump or an unusually long header at a higher elevation than the pump causing an idle pump to run backwards, you shouldn't need a non reverse ratchet.

If you don't have a check valve to protect the pump, that is another matter.

It may be a standard feature that is furnished with the pump motor anyway, so they bring it out as a feature.

I don't usually see them used, but that is just me.

rmw

 

[Barry1961]

Some VFD's have a canned routine to stop reverse rotation before starting.

Barry1961

 

[DAVIDSTECKER]

It sounds like what you are looking for is also know as an overrunning clutch.
Hilliard has a nice clutch series called Magna Torque that is very compact and has torque from 82 lb-ft to 43,600 lb-ft.
You can order your electric motor with a shaft out the other end then mount the clutch with a factory torque arm on it to stop the reverse rotation.
Hope this helps, David

 

[GregLocock]

One way bearings are used on long conveyor belts running up hill. Cost of the bearing itself is of the order of hundreds of dollars, so in the context of your project that is probably down in the weeds.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[DAVIDSTECKER]

The last clutch I recieved pricing on was just under $2,000.00 for a clutch with 4,910 lb-ft of torque.
Still concidering the it was bored, keyed, and had drilled and tapped bolt holes, it was a good value and I was able to fit it in to my design parameters very well.