Looks like insufficient braking power for the hill.Securing looks like it could have been better too. No further information. Comment of the editor: It looks like the platform trailer did not break at all!! The tires are still rolling, while the tractor tires of both units are full on their brakes, but obviously have not enough power to stop this heavy load rolling down a relatively steep slope. Question: Was the yellow brake line to control the brakes connected?? or did they just connect the red supply line to release the brakes?? httpv://youtu.be/nYKtTKZRegA Accidente ocurrido durante el traslado de una casa de Maquinas de Grua capacidad 400 ton. saquen sus propias conclusiones.