So modern armies have a lot of supplies they need to carry with them, and for centuries, they relied on horses, mules, and oxen pulling carts for their transportation. However, these draft animals require a lot of feed; in the American Civil War, the Army of the Potomac was feeding its tens of thousands of horses 25 lbs of feed a day. In terms of weight, that's enough for 5-10 men.
The rickshaw was only invented in the late 19th century, from what I'm seeing, but it looks to me like if you were able to substitute a portion of your horse drawn supply train with rickshaws (say, rotate men from a section through 1 hour shifts pulling it, switching during the hourly five minute halts), you could significantly lighten the army's supply load. You'd need more individual vehicles, but you have tons of 'engines' that as is are just pulling their own weight.