I like scissors jacks for the following reasons:
No fluid to leak, externally nor internally.
I have a hydraulic floor jack that I used in a non level situation removing a tree stump. It does not work any longer. The fluid apparently went into parts of the mechanism it should not have.
Scissors have a much greater range. I have an old "Big Boy" from my grandfather. It goes from 4" to 15". This is much smaller than a bottle jack. Don't forget, a jack that will fit under your trailer when the tires
are full may not when one is flat.
You can maybe get an old auto jack from a junk yard for $5. Half of the weight
of a 3500# trailer is 1750#, say 2K#. A ton and a half should be more than enough. Don't forget you pay for the weight
in gas mileage.
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