JACTON offers screw jacks with upright or inverted mounting, they are operate in tension or compression force.
The upright screw jacks are usually used to lift, press or push up objects(the screw end fittings are upper mounting base), most of them with compression load.
The inverted screw jacks are usually used to lift, pull or press down object(the screw end fittings are under mounting base), most of them with tension load.