There is no doubt now that we can create machines, driven by the force of gravity https://www.researchgate.net/publication/298045558_Method_for_converting_gravity_force_spring_force_and_force_of_permanent_magnets_in_a_rotary_motion.
My method of converting gravity force into rotary motion, described here: http://www.ipaustralia.com.au/applicant/zenin-vladimir-mr/patents/AU2013267055/, leads to the need to create complex engines.
In this article, I chose the way to explain the conversion method in models of a simple design. After that, the processes occurring in engines of complex design will be more understandable. I hope many of you are familiar with walking on the barrel. This little trick is some kind of pleaser (even if you fall off) and a fun way to transport barrels from one place to the other. Did you think that this walking uses the mentioned principle of the gravity force to rotary motion conversion? I think you will say no. The first man who demonstrated how to use the weight of his body for riding around on a decorated cylinder was G. S. Monohan an author of The Textbook of Roller-skating, https://books.google.com.au/books/about/The_Text_book_of_Roller_skating.html?id=XjdanQEACAAJ&redir_esc=y .
Unlike those who walk on the barrel making steps, Monohan did not make any steps, but simply skilfully kept his legs in such a state that his weight acted on the cylinder at an acute tangent angle to get the cylinder rotation. We clearly see it on this old photo. He could do this because he was a great master of balancing during roller-skating. More than 100 years have passed and now, we can call him the discoverer of a new era of using such a combination of wheels in which the vehicle becomes self-propelled using weight as the driving force.
The average Amtrak passenger car weighs about 65 tons. Therefore, an Amtrak train with one locomotive and six cars weighs about 540 tons, or 1.08 million pounds. That is just for the train. That does not include one single passenger https://en.wikipedia.org/wiki/Sydney_Trains_A_set. The heaviest trains in the world carry bulk traffic such as iron ore and coal. Loads can be 130 tonnes per wagon and tens of thousands of tonnes per train.
We do not have the experience and knowledge of the efficiency of the vehicle weight in motion conversion and can only assume that it will be enough not only for the vehicle running but also for the production of electricity needed for transport services. I hope so and propose the following idea to control the movement of a railway vehicle.
In the pictures the train is depicted as block installed on two pairs of main wheels. Additional wheels of smaller diameter carry the weight of this train, which can be placed on the main wheels to the left or to the right of their axis of rotation. This allows changing the direction of the train running, to brake it or keep it completely still. This does not exclude the use of a conventional braking system for the main wheels.