Well! If the patient has the weight of 70 KG, then you should try the 35 Kg of traction instead of 15 KG. 15 KG is too small weight to produce any therapeutic effects. Usually the lumbar traction applied is in range of 18 to 45 KG. AND 15 KG is not in that required range. That is the main problem here. So you should use the right weight to produce the effects. MOREOVER, make sure that foot end is raised while using the continuous traction.

Have a good day there.