According to Austrian Airlines, free baggage allowance on the fights between Europe and USA is as follows: each passenger holding an economy class adult ticket is entitled to bear the luggage of 1 bag max. 23 kg free of charge; any passenger holding a business class adult ticket is permitted to take the luggage of 2 bags max. 32 kg free of charge. A single item of hand baggage may not exceed the dimensions 55x40x23 cm and the weight of 8 kg. Anyway, you may consult Austrian Airlines for details.