By carefully controlling the release of spring energy to counteract the pull of gravity the counterbalance holds the lid open and balances the load in every intermediate position.
Sliding door counterbalance.
A coiled leaf spring mounted on the counterbalance assembly has its upper end.
A slidable counterbalance assembly adapted for a sash window assembly disposed within a master frame is disclosed.
A vertically operating door assembly comprising a door a pair of vertically disposed and rearwardly inclined tracks said door having rollers engageable in said tracks to guide the same for.
The todco counterbalance is calibrated to the door s weight and size to ensure reliable smooth operation.
The only problem is if the door actually closes shut though i could probably find a simple way of keeping the latch bolt of the door knob simply jamming it with a small piece of wood comes to mind.
No excessive force required to lift.
Unfortunately my door is a bit heavier it is an old wooden door but i ve oiled the hinges so it does open and close quite smoothly.
The counterbalance is one of the key strengths of a todco roll up door and not just because it provides the lift.
Lift slide counterbalance gear mechanism heavy doors counterbalance features.