Research and analysis of the video recording of the experiment on measuring the bending arrow of a cantilever fixed palladium plate, coated with copper on one side by the electrolytic method are carried out. The experiments are carried out in a hydrogen-vacuum plant at a temperature of 280°С, a change in pressure in the working chamber of the plant, and an increase in the hydrogen concentration in palladium by $\Delta n$ = 0.0053 = const. It is experimentally recorded that the bending of a palladium plate upon additional saturation with hydrogen at 280°С consists of two stages. First, the maximum bend is reached, which takes a few seconds. At the next, more prolonged stage, the plate is straightened with an almost initial state of the plate. It is experimentally shown for the first time that at 280°С the maximum plate bends decrease with an increase in the hydrogen concentration in palladium by the same amount at each puffing. The kinetics of the straightening process is the same and the plate bends are reversible. The physical reasons are discussed and an assumption is made that the special physical nature of the formation in the first seconds of the maximum bending of the plate is due to the formation of a temporary gradient $\alpha$-PdH$_n$ alloy with a certain thickness, which has other values of Young’s modulus, different from pure palladium. It is established for the first time that at $T$ = 280°С the thickness of the hydrogen-free layer in a palladium plate during the formation of a gradient $\alpha$-PdH$_n$ alloy depends on the hydrogen content in palladium and a decrease in this thickness occurs precisely in the region of ideal and pseudoideal solid solutions of hydrogen in palladium.