Sopwith cockpit.

As far as I recall , there is no winding handle on either of the Spad 7's Live ammo or Empty belt drums .

 Although there are a few drawings missing from the full set of S7 manufacturing drgs that unfortunately , just were not saved ....There is , as I said , a Conical spring brake on the Live ammo drum ahead of the pilot but the Empty belt drum *, being positioned on the LH side , just behind the pilot , would make it almost impossible for the pilot to reach & operate , even IF such a winding handle were present .

* Sadly , I do not have the drawings for this latter component , or its means of pre-tensioning .

The Pup/Strutter MG operation is a little more awkward than the Spad 7 in as much as the Pups "trigger" (? item#3 in your photo) as with the Scarff-Dybovsky gear , consisted of a tubular lever with a flattened end , which had to be depressed to fire the gun ...This was positioned to the left of the Vickers , just above the level of the top longerons ...

Thus neither the Tampier Fuel/Air throttle levers on the left side , nor the belt winding handle , could  be operated simultaniously by the Left hand  , while also depressing the MG trigger .

This system may?? have been superceeded by a trigger on the spade grip in later machines ?? to be operated by the right hand thumb .

On the Spad 7 , the Left hand would be free , ( to operate a winding handle IF it did exist ) & anyway , Both the Throttle & MG triggers are incorporated into the Control Column Handle , for right handed use ,... the throttle action coming from a twisting movement of the hand grip , the integral trigger and guard assembly moving with it .

JM