I've always been impressed by the construction of Hydrovac units- - - - -rugged, "no nonsense" pieces of equipment meant to last a long time and be repairable when necessary. They serve the same purpose as firewall mounted boosters- - - -"Make the driver's leg stronger"- - - - -but they do it better than less-robust equipment. Just looking at the diameter of the boost piston, and the stroke makes it appear that lots of brake fluid at a high pressure is available when needed. Some older motorhomes used two small hydrovacs with a split brake system, back in the 1970's. I believe they were plumbed in a "dual diagonal" configuration, where one rear wheel and the opposite front shared the same hydraulic system.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!