When the velocity of the piston reaches a certain value (about 8in/min),the hydraulic valve will shut off and the entire system is locked. i.e. that isthe piston movement is arrested.

When the velocity of the piston reaches a certain value (about 8in/min),the hydraulic valve will shut off and the entire system is locked. i.e. that isthe piston movement is arrested.
Hydraulic snubbers and mechanical snubbers can take the same loads if they are the same size snubber. It depends upon the load that each type of snubber is designed for.
Hydraulic Snubbers Designed for a Geothermal Facility
There is little difference in the initial dragforce associated with mechanical and hydraulic snubbers. Basically, both styles are designed to impart a maximum of 2% of their design restraint load during normal pipe deflection.
Mechanical Snubber
Please specify figure number,cylinder size, stroke, load, cold and hot piston settings, and piston endoption when ordering a mechanical or hydraulic snubber. If clamp is required, please specify nominal pipe size, or special O.D.and clamp material. Please specify or describe any additional optional featuresor special settings required.
Both snubbers function similarly. One thing to consider would be the environment. If the environment is real dirty, the mechanical snubbers may get gritty and not function properly. Likewise, if the environment is extremely cold, the fluid ina hydraulic snubber may not function properly. Additionally hydraulic snubbers have a larger available displacement, but basically the mechanical and hydraulic snubbers function similarly.
Mechanical Snubber
Hydraulic Snubber
Snubbers can be adjusted by either changing the initial position of the telescoping cylinder or by using (where available) the adjustable rod end feature to alter the length of the snubber.
Mechanical Snubber Assemblies
The basic working principal behind a hydraulic snubber is that under slow(normal) speeds, a piston moves within a hydraulic reservoir pushing hydraulicfluid from the front to the back (or visa versa) of that reservoir. When animpulse load occurs and the piston tries to move at a high speed, a valve willclose thereby restricting or blocking the movement of the fluid within thereservoir and subsequently locking the moving piston.
Hydraulic Snubber Assemblies
A hydraulic snubber is a device that permits pipe deflection under normal operating conditions, but when subjected to an impulse load, such as an earthquake, water hammer, etc., the snubber becomes activated and acts as a rigid restraint torestrict pipe movement as a result of the unwanted impulse loading.
A hydraulic snubber includes a hydraulic fluid reservoir and cylinder to produce the restraint force when activated.
Hydraulic Snubbers with Protective Boots