A device for simultaneously delivering substances from a plurality of syringes (16, 18) that have plungers (22, 24) and barrels, said device comprising: a handle; a syringe barrel supporting structure attached to the handle and constructed to support the barrels of at least first and second syringes (16, 18); a syringe plunger driving assembly engageable with the plungers (22, 24) of said at least first and second syringes (16, 18); and a screw mechanism (12, 14), including a rotatable shaft, useable to advance the syringe plunger driving assembly in a distal direction, thereby causing the syringe plungers (22, 24) to expel substances from the syringes (16, 18); the device being characterized in that the syringe plunger driving assembly comprises: a yoke assembly having an upper member and a lower member, at least one of said upper and lower members (42, 46) being moveable between an open position and a closed position; a cylindrical shaft receiving bore formed in said yoke assembly, one semi-cylindrical portion of that bore being formed in the upper member and an opposite semi-cylindrical portion of that bore being formed in the lower member; wherein the semi-cylindrical portion of the bore formed in the upper member is threaded so as to engage the threads on the shaft when the yoke assembly is in the closed position and an opposite semi-cylindrical portion of the bore formed in the lower member is substantially smooth and devoid of threads. a handle; a syringe barrel supporting structure attached to the handle and constructed to support the barrels of at least first and second syringes (16, 18); a syringe plunger driving assembly engageable with the plungers (22, 24) of said at least first and second syringes (16, 18); and a screw mechanism (12, 14), including a rotatable shaft, useable to advance the syringe plunger driving assembly in a distal direction, thereby causing the syringe plungers (22, 24) to expel substances from the syringes (16, 18); the device being characterized in that the syringe plunger driving assembly comprises: a yoke assembly having an upper member and a lower member, at least one of said upper and lower members (42, 46) being moveable between an open position and a closed position; a cylindrical shaft receiving bore formed in said yoke assembly, one semi-cylindrical portion of that bore being formed in the upper member and an opposite semi-cylindrical portion of that bore being formed in the lower member; wherein the semi-cylindrical portion of the bore formed in the upper member is threaded so as to engage the threads on the shaft when the yoke assembly is in the closed position and an opposite semi-cylindrical portion of the bore formed in the lower member is substantially smooth and devoid of threads. a yoke assembly having an upper member and a lower member, at least one of said upper and lower members (42, 46) being moveable between an open position and a closed position; a cylindrical shaft receiving bore formed in said yoke assembly, one semi-cylindrical portion of that bore being formed in the upper member and an opposite semi-cylindrical portion of that bore being formed in the lower member; wherein the semi-cylindrical portion of the bore formed in the upper member is threaded so as to engage the threads on the shaft when the yoke assembly is in the closed position and an opposite semi-cylindrical portion of the bore formed in the lower member is substantially smooth and devoid of threads.