PULL PULL Cylinder Removal tool Cylinder mouth Backup rings O-ring Extractor tool Removal spoon PUSH PULL Extractor tool Removal tool Backup ring Backup ring O-ring Extractor tool Removal tool PUSH PULL PUSH PULL Backup ring O-ring extractor tool O-ring removal tool Backup ring O-ring PUSH PULL Removal tool Cylinder mouth Cylinder Backup rings O-ring O-ring Extractor tool Backup rings Removal tool (hook type) Extractor tool (push type) Removal tool (hook type) Extractor tool (pull type) Removal tool (hook type) Extractor tool (wedge type) Removal tool (hook type) Extractor tool (hook type) Removal tool (hook type) Extractor tool (push type) Internal O-ring removal (using pull-type  extractor and hook-type removal tools) Dual internal O-ring removal (using push-type  extractor and hook-type removal tools) External O-ring removal (using spoon-type extractor removal tools) External O-ring removal (using wedge-type extractor and hook-type removal tools) Internal O-ring removal (using wedge-type extractor and hook-type removal tools) Internal O-ring removal (using push-type extractor and hook-type removal tools) A B C D E F Figure 12-60.  O-ring installation techniques. 12-39 servicing. The positive pressure in the reservoir ensures a  positive flow of fluid to the pumps. The reservoirs have a  standpipe that prevents the loss of all hydraulic fluid if a  leak develops in the  engine-driven pump or its related lines.  The engine-driven pump draws fluid through a standpipe in  the reservoir and the AC motor pump draws fluid from the  bottom of the reservoir. [Figure 12-63]