LVIT Linear Position Sensor LZ-33 Series

What Is the LZ-33 and What Makes It Different?

The LZ-33 Series LVIT (Linear Variable Inductance Transducer) from Alliance Sensors Group is a through-bore, frictionless linear position sensor designed for long-stroke measurement in factory automation, heavy vehicle suspension, and external hydraulic cylinder rod sensing applications. With a 1.315 inch (33.4 mm) OD aluminum or stainless steel body and measuring ranges from 150 mm to 900 mm (6 to 36 inches), the LZ-33 covers stroke lengths that smaller-diameter LVITs cannot reach while maintaining the contactless, wear-free operation that defines LVIT technology.

The through-bore design features a 0.670 inch (17 mm) bore through which a 0.645 inch (16.4 mm) diameter moving rod passes completely through the sensor body. This rod — made of the same material as the housing — acts as the inductive spoiler, and because it passes through rather than stopping inside the sensor, the LZ-33 is inherently protected against damage from mechanical overstroke. The overall sensor length is only 3 inches (76 mm) longer than the measurement range, delivering the excellent stroke-to-length ratio that LVIT technology is known for.

Why Choose a Through-Bore LVIT for Long-Stroke Measurement?

Overstroke Protection Built Into the Design

In many long-stroke applications — hydraulic cylinder rod sensing, suspension travel monitoring, chute and gate position feedback — mechanical overstroke is a real operational risk. If an actuator travels beyond its expected range due to a control fault, mechanical impact, or load shift, a sensor without overstroke protection can be damaged or destroyed. The LZ-33’s through-bore design eliminates this risk entirely: the moving rod simply passes further through the sensor body without contacting any internal stop. This means the LZ-33 survives overstroke events that would damage captive-rod sensors, reducing unplanned downtime and sensor replacement costs in applications where overtravel cannot be fully prevented.

Frictionless Contactless Measurement

The LZ-33 provides truly frictionless position measurement — there is no physical contact between the moving rod and the sensor body during operation. The position signal is generated by inductive coupling between the rod (acting as the spoiler) and the sensing coil, with no wipers, bearings, or sliding contacts in the measurement path. This frictionless operation means the LZ-33 does not impose any drag or side load on the measured object, and the sensor does not wear out from continuous cycling or dithering — making it ideal for high-cycle automation applications where potentiometers would fail from contact wear.

Key Applications for the LZ-33

Large Truck and Agricultural Vehicle Suspension

Heavy truck and agricultural equipment suspension systems require long-stroke position feedback to measure ride height, axle travel, and suspension displacement. The LZ-33’s 150–900 mm range covers these stroke requirements, and the through-bore design tolerates the overstroke events that occur during heavy loading, terrain impacts, and suspension bottoming. The contactless sensing principle is unaffected by the dust, mud, and moisture exposure common in on-highway and off-road environments, and the extended temperature range option (-40°C to 105°C) handles the full range of ambient conditions these vehicles encounter.

External Hydraulic Cylinder Rod Position Sensing

For hydraulic cylinders where an embedded in-cylinder sensor is not practical — due to cylinder design constraints, retrofit requirements, or the need for field serviceability — the LZ-33 mounts externally to sense rod position. The through-bore design allows the rod (or a parallel extension) to pass through the sensor, and the 33.4 mm OD body provides a robust mounting platform. The long stroke ranges and overstroke protection make the LZ-33 well-suited for large cylinders in industrial presses, construction equipment, and material handling systems.

Factory Automation, Assembly Machinery, and Packaging Equipment

In automated production lines, the LZ-33 provides position feedback for long-travel actuators, chute and gate positioning, assembly fixture alignment, and packaging machine carriage position. The frictionless operation eliminates the sensor as a maintenance item in high-cycle applications, and the DC-in/DC-out architecture connects directly to PLCs and motion controllers without external signal conditioning.

Chute, Gate, and Damper Position Monitoring

Material handling chutes, diverter gates, and damper assemblies often require position feedback over stroke lengths of 12–36 inches with overstroke tolerance. The LZ-33’s combination of long range, through-bore overstroke protection, and contactless operation makes it a natural fit for these applications, where the sensor must survive the mechanical abuse of heavy material flow and occasional jam-induced overtravel.

LZ-33 Stroke-to-Length Ratio: Why It Matters for Long-Range Measurement

At only 3 inches (76 mm) longer than the measurement range, the LZ-33 consumes minimal additional mounting space beyond the stroke it measures. A 24-inch (600 mm) range LZ-33 is only 27 inches (686 mm) long — compared to an AC-LVDT of equivalent range that would require significantly more body length to accommodate the primary and secondary coil windings. For engineers designing long-stroke measurement into space-constrained equipment, this compact envelope can be the determining factor in sensor selection.

Electrical Output and Field Calibration

DC-In/DC-Out with Standard Industrial Outputs

The LZ-33 operates from 8–30 VDC input and provides conditioned analog output directly: 0–5 V, 0.5–4.5 V, 0–10 V, or 4–20 mA, with reverse-acting versions available. No external signal conditioner is required. Radial cable exit (1 m or 3 m) routes wiring along the machine structure rather than extending from the sensor end.

SenSet™ Field Programmability

All LZ-33 sensors include ASG’s SenSet™ feature for zero and full-scale adjustment at the point of installation. This allows the output to be matched to the actual mechanical range of motion without factory recalibration — particularly useful for OEM builders using the same sensor across machines with different stroke requirements.

Key Specifications

Measuring ranges: 150 mm to 900 mm (6 to 36 inches) full scale

Through-bore: 0.670 inch (17 mm) bore, 0.645 inch (16.4 mm) rod diameter

Housing: 1.315 inch (33.4 mm) OD, aluminum or 300 series stainless steel

Overall length: measurement range + 3 inches (76 mm)

Linearity error: ±0.15% FSO typical, ±0.25% FSO maximum

Resolution: 0.025% of full scale output

Update rate: 300 Hz nominal

Shock: 1,000 g, 11 msec

Vibration: 5–20 Hz at 0.5 inch p-p; 20–2,000 Hz at 4.2 g p-p

Operating temperature: -20°C to 85°C (-40°C to 105°C extended range)

Temperature coefficient: ≤0.015% FS/°C

Termination: radial cable exit, 1 m or 3 m, IP67

Need help selecting the right LZ-33 configuration for your application? Contact Alliance Sensors Group’s application engineering team at alliancesensors.com or call 856-727-0250.