HEAD 6E3972 - Caterpillar

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Operation of Snubber with a Retracting Cylinder Rod (5) Snubber (6) PassageWhen the stick cylinder comes close to the end of the retraction stroke, passage (6) is restricted by snubber (5). The movement of the piston rod slows down before the piston stops. This action absorbs the shock load at the end of the retraction stroke.Snubber
Head End
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(7) Rod (8) Cylinder
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(9) Check valve (10) Port (inlet and/or outlet) (11) Snubber (head end) (12) Cylinder (13) Piston area
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(10) Port (inlet and/or outlet) (13) Piston area (14) Cylinder (point of restriction for hydraulic oil flow) (15) Piston (rod assembly)Snubber (11) for the head end of the cylinder rod restricts the flow of hydraulic oil in piston area (13) of the cylinder.When rod (7) is retracting into cylinder (8), the hydraulic oil flows from piston area (13) to hydraulic port (10) and to the head end of the cylinder. As the cylinder rod approaches the back of the cylinder, the hydraulic passage between snubber (11) and cylinder (12) closes. This action restricts the flow of hydraulic oil from piston area (13) into port (10). As the cylinder rod moves snubber (211) into port (10), the hydraulic passage is closed and no hydraulic oil can flow from piston area (13). The reduction in flow increases the pressure in piston area (13). This condition slows the motion of the cylinder rod to a stop.During the retraction of the rod, snubber (11) on the end of cylinder rod (7) slows the motion of the rod assembly into the cylinder head.Head End Check Valves
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(7) Rod (8) Cylinder
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(9) Check valve (10) Port (inlet and/or outlet) (11) Snubber (head end) (12) Cylinder (13) Piston area
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(10) Port (inlet and/or outlet) (12) Cylinder (13) Piston area (15) Piston (rod assembly)Check valve (9) allows hydraulic oil to enter piston area (13) in order to force cylinder rod (7) out of cylinder (8) .During cylinder extension, the hydraulic oil pushes piston (15) and the face of snubber (11) in order to force cylinder rod (7) outward. When the cylinder is fully retracted, port (10) is blocked to piston area (13) because the port is sealed by snubber (11). When hydraulic oil is forced into port (10) in order to extend the rod assembly, check valve (9) opens in order to allow hydraulic oil to flow from port (10) to piston area (13). Since the hydraulic oil passes through check valve (9), the oil is able to push piston (15) in order to move the rod assembly out of the cylinder. Now, hydraulic oil pushes the face of snubber (11) with piston (15) in order to move the rod assembly out of the cylinder. Without the passage that is created by check valve (9), hydraulic oil could only push the face of snubber (11). The contact surface area for the hydraulic oil increases when piston area (13) opens to port (10) .Rod End
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View of the Cylinder Rod End with the Retracted Rod Assembly (16) Rod