Connecting a washing machine and tumble dryer to the same sink drain
As indicated by isherwood your air gaps are mandatory. This is to prevent return of waste water into the appliance. In your setup you have an air gap but only one and also only one trap. It is better to construct separate air gaps and traps for each unit and combine both after the traps into the sink.

Construction can be straight forward: 
Take 2 traps and combine the outlets. Place some 10 to 12" pipe on top of the trap and put the appliance hose directly inside without a seal. The gap is then formed by means of the space between the hose and the pipe.