There are four types for the hydraulic tensioning jack:
1) THA is a general one, which is used with the simple srew rod, and it contains hydraulic cylinder with strentch;
2)THB is an Interchangeable one. It is made up for strentch, cylinder and support bridge, which can match several strentches in alike specifications.
3)THC is a single-stage automatic reset one. The only difference from THB is that it adds reset system.
4)THD is a bi-stage automatic reset one. It has two cylinders comparing to THC.