Product Overview

The Graco 527-003-250​ is a cycle indicator proximity switch from the Graco Lubriquip automatic lubrication programme, engineered to give a lubrication controller or PLC positive confirmation that a series-progressive divider valve has actually cycled. Supplied under the legacy Lubriquip part numbering scheme that Graco retained after acquiring the Lubriquip and Trabon lines, the Graco Lubriquip 527-003-250​ belongs to the same Trabon cycle proximity switch family as part 527-003-251, which Graco cross-references to its current part number 557741. In that family, Graco offers Reed type, Field Sensing Magnetic (FSM), magnetically operated snap-action and solid state designs, all of which are magnetically actuated single-throw devices that sense the movement of the divider valve piston as it cycles.The operating principle is straightforward but critical. The Graco 527-003-250​ is installed in place of an O-ring sealed piston enclosure plug in one working section of a series-progressive divider valve assembly. As lubricant is pumped through the valve, the metering piston reciprocates; each time it approaches the switch, the internal magnet or sensing element changes state, and each time it retracts the switch returns. Those two transitions — open-to-closed and closed-to-open — are read by the controller as one complete cycle of that divider section, and therefore one complete cycle of the entire valve assembly.In an automation architecture, the Graco 527-003-250​ is what turns an open-loop lubrication timer into a closed-loop, verified lubrication system. Instead of assuming that grease reached a bearing because the pump ran, the controller knows it, because the switch reported the piston movement. When the expected pulse train stops arriving, the system raises a blocked line, pump failure or empty reservoir alarm before the bearing runs dry.

Technical Specifications

Note: The Graco Lubriquip numbering scheme encodes connector type, pin count, voltage and LED option. Verify the electrical variant against your existing unit or the Graco cross-reference before ordering.

Main Features and Advantages

Positive confirmation rather than assumed delivery: The core value of the Graco 527-003-250​ is that it reports actual metering piston movement rather than pump runtime. A lubrication controller or PLC counts the pulses and compares them with the programmed target; if the count is not reached within the expected run time, the system declares a fault. This is the difference between a machine that is lubricated and a machine whose lubrication is verified, and it is the reason cycle switches are specified on critical bearings in presses, mills and continuous process lines.Magnetically operated, non-contact sensing: Because the Graco 527-003-250​ is actuated by the magnetic field or mass of the moving piston rather than by a mechanical plunger bearing on it, there is no contact force, no wear interface and no drag on the metering piston. Field sensing magnetic designs in this family are rated for tens of millions of cycles, and solid state variants for up to 200 million, so the switch outlasts the mechanical life of the machine it protects.Built for the lubrication environment: The Graco 527-003-250​ uses a 303 stainless steel body with a Buna-N O-ring seal so that it holds pressure and resists grease, oil, cutting fluid, road salt and washdown. It installs directly into the divider valve body, which means no brackets, no target plates and no alignment fixtures — the sensing target is the piston that is already there.Electrical flexibility for any control architecture: Variants in this family cover 24 VDC and 115 / 240 VAC operation with 3, 4 or 5 pin Brad Harrison or Crouse Hinds connectors, M12 × 1 four-pin connections, ½ in. NPT conduit on Reed types, and pigtail leads on explosion-proof models. The Graco 527-003-250​ can therefore be matched to a DC PLC input card, an AC controller input or a hazardous location installation without an interface relay.Local diagnostics where it matters: DC variants with integral LEDs give maintenance technicians a visible blink at the divider valve each time the piston cycles, so a suspected blocked line can be confirmed or ruled out on the spot. This turns a troubleshooting exercise that could take an hour of tracing wiring into a five-second visual check at the valve.System-level consequences of failure are designed in: If the Graco 527-003-250​ stops signalling, the controller does not simply continue; it alarms on flow fault, pump failure or divider fault and, in most configurations, prevents the host machine from continuing to run unlubricated. The sensor is therefore a protective device, not merely a monitoring convenience.