Q:

What was Masada's Roman ramp steep angle?

One thing that puzzled me about the story of Masada, is the ramp for the ram.
The angle looked bizarre to me. I suppose it wore out over the years by the harsh winds, and maybe floods, but from models over the web (e.g. Google Earth and other models), it should be about 25 degrees.
The Romans were indeed gifted engineers but in order to pull a tower that weighs, say, 10 tons in 25°, you need about 4.5 tons of force + friction. Not sure they had the technology for keeping it intact all the way up. Not sure we have the technology.
What am I missing?

A:

What am I missing?

Alex points out in comments that a machine may be transported in sections, and this was apparently the intent here.  A 19th century article in the Cyclopædia of Biblical, Theological, and Ecclesiastical Literature, Volume 12
By John McClintock, James Strong, concerning this construction has this to say (emphasis mine):

The
  second path on the west ascends from a narrow sloping bank of white
  marl which is about 1000 feet high and which Josephus calls the White
  Promontory upon this rises the great ramp about 300 feet high which
  the Romans piled up against the rock during the siege, a work so
  laborious that it seems almost incredible that human efforts could
  have accomplished it in so short a time. At the top of the ramp is
  the masonry wall which the besiegers built as a foundation for
  their engines before discovering the great tragedy that had been
  enacted within the fortress where the garrison had fallen by one
  another's swords

So the seige machinery was to be constructed at the top of the ramp, not pulled up the ramp itself.
Note: If you are still interested in some more recent information concerning this siege, a more recent publication which has some good discussion is Making History: Josephus And Historical Method
edited by Zuleika Rodgers.  (This lists several sources of other articles discussing the ramp, most of which are modern publications so aren't falling into the viewable category on Google books.) This article does provide some good dimensions for a different ramp, one built by Caesar, which was 23.5 meters high, 97 meters in length and 50 meters wide. You might use this as a comparison for your calculations.

