LIFT BRIDGE OVER THE MURRAY AT SWAN HILL. XCVII. 
gearing into the two rope wheels over upstream towers, whilst 
the two longitudinal shafts driving the four rope wheels are 
connected by mitre wheels keyed to a transverse shaft, the uniform 
working of lift span being thus ensured. 
The total weight of the lift span is thirty-four and a-quarter 
tons, and is so far counterweighted that a maximum weight of 
18001bs. has to be raised or lowered, one man with ease raising or 
lowering span through 25’ 10” in 55 minutes or at the rate of 4:7’ 
per minute. 
It may be here noticed that the Brewarrina bridge with its 
“endless” chain is balanced in all positions, but at Swan Hill 
the lift span is only in balance when opposite the counterweights, 
hecessitating provision being made in the latter bridge for lifting 
the unbalanced ropes, this weight however is more than com- 
pensated for by the reduction in frictional resistance obtained 
with ropes in lieu of chains and sprocket wheels. 
The Swan Hill bridge differs from previous lift bridges in this 
Colony, in which wire ropes have been adopted, in the following 
respects—the lift is 5’ 10” higher, the machinery platform is placed 
at deck level thus avoiding the time lost by man climbing towers 
and making his way to an overhead winch, whilst the disposition 
and design of lifting gear is altogether new, again the absence 
of an overhead machinery platform relieves the deep longitudinal 
Sirders in the Swan Hill bridge of considerable weight, thus 
Preventing any deflection in the girders, with the accompanying 
“ pinching ” of the shafts. Boe 
The gearing and shafting throughout the author's design is 
very much lighter, the pitch of teeth of pinion on the shaft 
driving rope wheels being only 14” as against 24” and on the first 
motion shaft 2” as against 1}” in previous bridges. 
Again the adoption in the Swan Hill bridge of eight cast-iron 
boxes filled with lead for each counterweight, in lieu of a balance 
Weight formed of a cast-iron bottom section weighing four and three- 
quarter tons with a cast-iron top section filled with lead, facilitates 
7—Aug 19, 1896, 
