Jar Accelerator 3 : A hydraulic tool used in conjunction with a jar. The accelerator is made up in the fishing string above the jar and serves to increase the magnitude of the jarring blow delivered to the fish. (WLOP)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}