Subject: Re: [Shop-talk] filling a floor jack

From: "Randall" <[email-masked]>
Date: Fri, 27 May 2016 04:42:30 -0400

> My dilemma is how does one go about filling the hydraulic fluid on a floor
> jack? I lifted the arm all the way up, opened up the fill hole but was
> only able to put a little bit of fluid in before it was full. 

Did you wait for the oil to run down and try again?  On my floor jack it
takes a fair length of time for the oil to run down and level out.

Also, lifting the arm up may fill the cylinder with air.  Suggest instead
you pump it up as high as it will go, add oil, repeat.

Randall

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From: "Tim ." <[email-masked]>
Date: Fri, 27 May 2016 10:15:32 +0000

"Did you wait for the oil to run down and try again?"

I didn't wait but will this weekend. 

"Also, lifting the arm up may fill the cylinder with air."

Not sure how air could get in with the plug still in?

"Suggest instead you pump it up as high as it will go, add oil, repeat."

But if I pump it up and then remove the fill plug won't that cause the pressure to release and the arm to come down pushing out even more fluid onto the floor? 

Thanks and keep 'em coming!
tim
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From: Shop-talk <[email-masked]> on behalf of Randall <[email-masked]>
Sent: Friday, May 27, 2016 3:42 AM
To: 'Shop  Talk'
Subject: Re: [Shop-talk] filling a floor jack

Randall

[email-masked]

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From: "Randall" <[email-masked]>
Date: Fri, 27 May 2016 08:48:53 -0400

> Not sure how air could get in with the plug still in?

The outer part is an oil reservoir.  Somewhere, there is a small vent that
allows air to enter the top of the reservoir as the pump sucks oil from the
bottom and forces it into the inner pressure cylinder (which in turn extends
the piston and moves the jack arm).

When the reservoir goes empty (because it is low on oil), the pump starts
sucking air, which gets into the inner cylinder, and obviously isn't so good
at forcing the piston out to raise a load.  You will eventually have to work
the air back out (by raising and lowering the jack with the reservoir
filled, perhaps several times) to get it working again; and then check the
reservoir level again.

> But if I pump it up and then remove the fill plug won't that cause the
> pressure to release and the arm to come down pushing out even more fluid
> onto the floor?

The plug just opens into that reservoir.  It does serve as a test port, so
you could possibly get some oil dribbling out under some circumstances; but
it won't be under pressure.

At least that's the way it's been on every floor and bottle jack I've ever
owned.

Randall

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