Reversing polarity on cooling fan

[culminator]

I'm in the process of fitting a new rad and would like the fan to be on the rear of the rad, rather than on the front as it is currently. Is it simply a case of swapping the wires at the connector end in order to reverse polarity in order to convert a "pusher" fan to a "puller" fan?

Cheers
Mike

[curley]

Mike
have a think about the blade shape .............................Does a propeller plane reverse its engines when it wants to go backwards ?

[culminator]

I had the very same thought 5 minutes ago! Thanks, you've answered my question.

[BertBert]

curley said:

Mike
have a think about the blade shape .............................Does a propeller plane reverse its engines when it wants to go backwards ?

What a cracking answer. How does that help?

[anonymous-user]

BertBert said:

curley said:

Mike
have a think about the blade shape .............................Does a propeller plane reverse its engines when it wants to go backwards ?

What a cracking answer. How does that help?

To put it another way, there's more to reversing the flow through a fan than simply reversing it's direction of rotation.

[k20erham]

Mount it on the back and run the motor the other way,, sorted, yes most prop aircraft will reverse with prop thrust if they have whats called beta range, they also use it as a brake when taxying to save the brakes, although you have to watch the turbine temps,

[rdodger]

Yes and no.

It will work but probably not as well as a fan built to pull.

Most fans have profiled blades to work more efficiently in one direction. Spinning it in the wrong direction may lead to high levels of noise and or vibration.

Some makes of fan can be reversed by removing the blades and fitting them the other way around. Best to check with the manufacturer or buy a puller.

[culminator]

I've decided to leave it as it is. If I end up removing the anti roll bar, which is probably not really needed with pushrod suspension, then I'll get a puller fan and mount that on the back of the rad. Just waiting on the new rad being delivered so i can drive my new toy!

Cheers
Mike

[anonymous-user]

rdodger said:

Most fans have profiled blades to work more efficiently in one direction. Spinning it in the wrong direction may lead to high levels of noise and or vibration.

Might also lead to no air actually being moved anywhere. The flow over the blades could stall, the air around the fan just cavitates and nothing actually happens.

Edited by anonymous-user on Wednesday 26th March 14:36

[BBL-Sean]

Ain't broke? Don't fix!

[BertBert]

k20erham said:

Mount it on the back and run the motor the other way,, sorted, yes most prop aircraft will reverse with prop thrust if they have whats called beta range, they also use it as a brake when taxying to save the brakes, although you have to watch the turbine temps,

But do they reverse the rotation of the prop? I'm no expert, but I think not.
Bert

[anonymous-user]

BertBert said:

k20erham said:

Mount it on the back and run the motor the other way,, sorted, yes most prop aircraft will reverse with prop thrust if they have whats called beta range, they also use it as a brake when taxying to save the brakes, although you have to watch the turbine temps,

But do they reverse the rotation of the prop?

No.

[BertBert]

Crossflow Kid said:

No.

Presumably variable pitch prop?

[anonymous-user]

BertBert said:

Crossflow Kid said:

No.

Presumably variable pitch prop?

Presumably, yes.

[BertBert]

I was presuming you'd be knowing, being in the trade and all.
Bert