I just found this link. Lots of great artillery photos

[rifleshooter2]

http://svsm.org/gallery/Artillery
 
In the smoothbore section there is a great series on the rodman gun mount.
 
Andy

[seacoastartillery]

     Thanks Andy, there are some great photos here and we like the Rodman carriage ones you pointed out.  The set we took the following pics from is the one under the smooth bore photos batch which has a Rodman tube lying on some timbers, but mentions the barbette carriage in the photo's description.

     We hope by using five of these pics we can point out some important Rodman carriage features and how they assisted the period artillerymen in operating those carriages in the later half of the 19th century.

T&M

There are significant clues in this photo as to the method of operation of this Rodman carriage.  This first is  ‘double dimples’ on the lower axle end and only a single dimple on the upper axle.   Presence of double dimples means that the lower axle is an ‘eccentric axle’ or an axle whose bearing surfaces were turned on two separate axes.  The center dimple  represents the axis upon which the central portion of the eccentric axle was lathe-turned.  This is the part which supports the carriage cheeks in bronze bearings.  The outer dimple represents the axis upon which the two eccentric axle ends were lathe-turned,  which rotates around the central axis, causing the engagement or disengagement of the two wheels, raising or lowering the carriage, accordingly.  A six foot long, iron, eccentric axle wrench is placed on both hex-shaped axle ends and drawn back toward the carriage’s rear to engage the wheels upon the circular pedestal plate which lifts the chassis’ pintle plate off of it and transfers most of the tube and carriage weight to the wheels.  This allows this heavy gun and carriage to traverse left and right allowing different targets to be engaged.





 In this shot you can see an important safety feature of this carriage.  The eccentric axle go through two cast iron risers which elevate the gun tube so that it can clear the top of the parapet and be a true barbette carriage.  The feature we ask you to look at is the end of the eccentric axle bearing sleeve on the far side where a notch can be seen.  This cast-in notch feature limits rotation of the eccentric axle wheels to a position just past ‘bottom-dead-center’ via a stout pin which protrudes from a hole in the axle.  This safety feature prevents the eccentric axle from dislodging from it’s ‘engaged’ position and letting the carriage and tube crash down on the pedestal plate unexpectedly.




 You can see that some changes to the basic Rodman carriage chassis were to help the Artillerymen get the tube back into battery after reloading.  That thing bolted to the forward chassis transom is a sheave with the carriage return cable pulley inside it.  The cable was attached to the eyebolt visible, went around the pulley and back through the hole in the transom to a similar hole in the rearmost chassis transom and around the cable drum visible in the photo after this one. 





 

[seacoastartillery]

     Here are two more pics which show vital features of this 10" Rodman carriage.

Tracy


  This view of the rear of the chassis shows the Return to Battery Cable Drum and large gears attached to it’s shaft.  On this side of the chassis there is what looks like a small gear engaged with the bottom of the large gear, albeit minus a small gear Hand Crank to match one which should be on the opposite side.  Rigid carriage stops are bolted to the chassis rail tops to prevent catastrophy, but we like the 100 Pdr. Parrott stops better.  They are actually adjustable compressor type brakes which slow the carriage gradually.  They can be tightened if you have rainwater on the rails or icy conditions.




 
You can see only one dimple at the end of the front, upper carriage, axle meaning that this is NOT an eccentric axle.  However, the rear axle is and the tip off is the socket attached to it.  A handspike is thrust into it and then pulled toward the back of the carriage to engage the eccentrics , lower the wheels and raise the rear of the carriage up.  This takes almost all of the weight off the front of the carriage bottom and enables the  Return to Battery Cable System to drag the Upper Carriage forward.  The rear traverse wheels and their long forks are also seen here.  After the front eccentrics are engaged, two Artillerymen can easily push the rear of the chassis left or right, rolling the traverse wheels on the circular track provided.