How can I use door opening to open separate flap with levers?

I am searching for a mechanical solution for my gate with lever and counterweights.

The space under my gate is too large when closed and my dogs can escape under. However the door opens up on an incline and if I put a wood flap on the bottom it would prevent it from opening fully due to the incline.

I'd like the flap to open up as the door swings open using pulleys and counterweights but can't figure it out.

Does anyone have suggestions?

Here is a drawing of the gate and how it slopes. It is at the top of a set of stairs from the sidewalk.

Here is a picture of the gate from the outside. Opens inward, slopes upward from there.

• Does the grade slope away or downhill on the opposite side of the gate, I.E. the side it swing away from ? – Alaska Man Apr 27 '20 at 17:55
• I'm on a hill. The fence and gate are at the top of the stairs and the hill continues to slope up. The gate opens in because if you open out you get forced down the stairs. I was thinking the flap would open up inwards so the when closed the dogs can't push it out. I tried to rig up something that you can see. It's not lifting it up fast enough and doesnt lower it. How do I post a picture? – Stumpedgateproblem Apr 27 '20 at 18:33
• Welcome to the site. Please register your account and then merge them so you have access to edit, comment, and accept answers on your own question. Posting multiple responses as answers can result in an automated lock that can prevent others from assisting you. – BMitch Apr 27 '20 at 19:02
• right now your hinges are arranged along a vertical axis, so the gate swings in a horizontal plane ..... arrange the hinges at a slight angle, so that the gate swings along the plane parallel to the ground – jsotola Apr 27 '20 at 19:44
• @fred_dot_u, the problem with off-vertical hinges is that the gate will slam shut with force – jsotola Apr 27 '20 at 21:05