I have a Topcon GTS-4 that has upper and lower plate clamps, but only an upper plate tangent screw. Claude couldn't find any use for the lower plate clamp, and the only mention of it in the GTS-4 manual is in reference to the picture. There is no mention in the usage scenarios, or packing for transit. More recent instruments in the GTS series don't seem to have the lower clamp anymore. Does anyone know what the lower clamp is for? Could it be for servicing? Or maybe its just leftover from the optical instruments like the GTS-2 that came before?
Is is there so your 'new guy' can loosen it midway through a topo and waste half of your day. 😱
I have a Topcon GTS-4 that has upper and lower plate clamps, but only an upper plate tangent screw.
We used a Topcon GTS-4, I think it was a GTS-4A, for an FDOT project in 1994. We thought it was a good instrument. The lower clamp is used for taking a backsight. We turned 8 sets of angles for our primary control points and advanced the horizontal plate for each backsight within those sets. I had my instrument man advance the plate by 45° for each backsight. See the blue arrow in the below picture? To my recollection, that's the lower plate clamp.