# How does a hydraulic spool valve work?

== == == == Spool dynamics include fluid motion actuated by one or more tangential forces, i.e, gears, and thus achieve force as a function of mass acceleration. Mass of small gas engine flywheel spins, creating torque, applied through a coupler into a hydraulic motor, oh no, more gears, only in reverse centripital motion. Vector forve applied in the Z direction produces torque that we all view as "the thingy moves" in laymans terms. As fluid speed increases, the puport functions only as a momentary divider of said spool. Once the area gradient w is selected, the minimum value of the spool diameter is determined because ports may be at most full periphery of the spool. The fluid then spools through the value hydraulically actuating the valve. The cylinder fills with fluid and extends much like the phalic symbol of a man. A man with many spools is a man hard stopped.

Typical passage in spool valves. It is possible to obtain a design relation between if and rtm from a consideration of flow saturation and valve.

Single-stage servovalves consist of a torque motor which is directly attached to and positions a spool valve. Because torque motors have limited power ...or do they, I'll won't mention it, it may confuse you terribly.

Note that two feedback loops are involved, and these are due to spool position feedback and to pressure feedback on the flapper. Because either loop could ...

With Kvp now known and selecting a suitable value for the spool actuation area Ar, we may use (7-82) %theta to determine the required flow gain of the pilot. Once angular momentum is initiated we then take the tangental derivative to achieve output. Big output.

Neglecting the flow force on the spool, cof -*• 0, and this equa- tion reduces. These equations can now be combined to form the block diagram. Spool valve dimensions are sized to satisfy load flow and pressure requirements. The flapper valve gain is determined from (7-100), and the other flapper ...

This backlash is due to slipping of the mechanical anchorages in the torque motor, but it is mainly due to friction between spool and sleeve. ...

This may amount to 0.0001 in. or so of main spool motion. The dither amplitude should not be so large that it is transmitted to the load by the servovalve ...

A spool type servovalve ports fluid to a piston or rotary motor whose motion is Ted back through some mechanical arrangement to stroke ...

These valves usually employ spool type construction and may be actuated manually, mechanically, hydraulically, pneumatically, electrically, ...

These four equations can be combined to form the block diagram in Fig. 12-5. The loop gain function for this loop is Ads) Pilot spool dynamics (

A. where Kv = flow gain of pilot spool valve, in.3/sec/in. (12-12) o>A = hydraulic natural frequency due to trapped oil spring and swash plate mass.