A priority system has a valve assembly which has an inlet, first and second outlets, and apparatus for controllably limiting fluid pressure at the first outlet to a preselected maximum value by controllably communicating the second outlet with the inlet. The priority system has a fluid reservoir, a work element and control apparatus connected to the work element, second outlet and reservoir which receives fluid from the second outlet and passes the fluid to the fluid reservoir or work element.
For work vehicles, for example, cold weather can be a problem. Disengaging the vehicle clutch (26) aids starting by reducing engine loads during starting. Where the clutch (26) is hydraulically actuated, it can be disengaged by keeping fluid pressures below required engagement pressure when supplying other elements common to the clutch hydraulic circuit. Apparatus is provided which during starting directs fluid to, for example, pump drive bearings (20) at less than clutch engagement pressure. An input signal to the apparatus from the vehicle operator after engine start-up then builds pressure to activate the clutch (26) while continuing to supply the pump drive bearings (20) for lubrication. Upon a preselected fluid flow to the apparatus, such as at engine shutdown, the apparatus automatically returns to the condition at which available pressure levels are less than required for clutch engagement. Thus, cold starting problems are substantially eliminated by automatically providing a clutch disengaged situation in the vehicle during engine start-up.
In a working vehicle comprising a hydraulic power steering cylinder (25) and hydraulic lift cylinder (31), a novel hydraulic system is employed which comprises first and second flow control valve means (47, 48; 147, 148; 247, 248; 347, 348), each dividing its inflow into two flows. These valve means are connected in a fashion such that output flow of a single pump (43) driven by engine (10) is first divided into two output flows one of which is then divided by the second valve means. Further, one of the output flows of the second valve means is directed towards the steering cylinder whereas the other of output flows of the both valve means are directed towards the lift cylinder. The connection is such that, while a predetermined constant flow is secured for the steering cylinder at the normal engine speeds, a flow is necessarily secured for a relatively quick operation of the lift cylinder already at a low engine speed.
A reversing and adjustment mechanism, especially for a reversible plough adapted for hydraulically adjustable furrow width and hydraulic reversing of the plough, wherein the reversing and adjustment mechanism comprises a hydraulic cylinder (8) with a "hydraulic memory" for adjustment of the furrow width. The oil chambers on both sides of the ordinary piston (15) in the adjustment cylinder (8) communicate with a reservoir (24) via two pilot-controlled check valves (26, 25) with open passage toward the adjustment cylinder (8) and a second direction-control valve (10). The chamber (31) in the adjustment cylinder (8) between the rear head and a freely movable piston (17) communicates on the one hand with a hydraulic cylinder (7) for reversing the plough, preferably with the rod end thereof, via a first check valve (14) with open passage toward the reversing cylinder (7), and on the other hand communicates with the reservoir (24) via a flow-control valve (28) and a first direction-control valve (9). The reversing cylinder (7), on the end opposite its rod; i.e., preferably on the piston end, communicates on the one hand with the rod end of the adjustment cylinder (8) via a pilot-controlled check valve (36) with open passage toward the reversing cylinder (7) and a pilot-controlled check valve (32) with open passage toward the adjustment cylinder (8), and on other hand communicates with the reservoir (24) via a pilot-controlled check valve (36), the reversible flow-control valve (28) and a first direction-control valve (9).
A process for making alternate S and Z twist plied yarn from individual singles yarns includes the steps of tensioning the singles yarns as they move in a path through the process, twisting the individual yarns in either an S or Z direction, stopping the forward movement of the yarn, then bonding the ply-twisted yarns at a node while applying twist, stopping the twisting operation, then repeating the procedure while twisting in the opposite direction.
A hydraulically powered fan system for the cooling system of a vehicle. Two hydraulic motors, powered by a hydraulic pump, drive a common fan which cools a radiator. When hydraulic flow in excess of that required to power a single motor is present, a second motor is placed in parallel with the single motor, thereby reducing system pressure, and reducing the power consumed by the pump.
