When you mention "la" rampa es muy pesada you are mentioning the ramp specifically, in correct Spanish you need to have the proper definition of gender.
Again " no se baje a mano" is specifying what not to do by hand, no baje does not specify what it is that you do not want to be lowered and in reality (no baje) means that the person is not to go down and not the ramp.
All of the four farces go together as one complete instruction rather than separate farces, and grammatically it is correct even in "Mexican" Spanish.
Translating from English to Spanish literally is not good to convey the same meaning, yes "no baje la rampa a mano" can be used but "no se baje" is more of a direct order of what not to do, otherwise what is being meant by "no baje la rampa a mano" means do not go down the ramp on your hands.
Use the four sentences together they are correct and convey the correct meaning.
Peligro
La rampa es muy pesada
No se baje a mano
Utilice el malacate manual dentro del vehiculo
navegator