Koehler K18850/K18851/K18852/K18853 Series Low-Temperature Grease Torque Tester

Overview

The Koehler K18850/K18851/K18852/K18853 Series Low-Temperature Grease Torque Tester is a precision-engineered laboratory instrument designed to quantify the rotational resistance of lubricating greases under controlled sub-ambient conditions. It operates on the principle of measuring torque required to initiate and sustain rotation of a standardized spindle immersed in grease at specified low temperatures—directly reflecting real-world performance in cold-start applications such as automotive wheel bearings, aerospace actuators, and industrial gearboxes. The system complies strictly with three key ASTM standards: D1478 (Low-Temperature Torque of Lubricating Grease), D4693 (Low-Temperature Torque of Lubricating Grease in Bearings), and D4950 (Classification and Specification of Lubricating Grease for Automotive Chassis and Wheel Bearings). Its dual-sample chamber architecture enables comparative evaluation of formulation variants or batch consistency under identical thermal and mechanical conditions.

Key Features

• Hermetically sealed mechanical cascade refrigeration system delivering stable, reproducible cooling to –54 °C standard or –73 °C optional—fully meeting ASTM D1478 and D4693 temperature requirements.
• Polished stainless steel insulated test chamber with integrated thermal management, mounted on heavy-duty leveling casters for lab-floor stability and mobility.
• Dual independent LED digital displays showing real-time torque (in oz·in or N·m) and chamber temperature for both test positions; for ASTM D4693 mode, additional display of individual spindle temperature is provided.
• Precision 1 rpm constant-speed drive motor coupled to calibrated torsion shafts, enabling accurate measurement of breakaway (starting) torque, running torque, and time-to-rotation metrics.
• Integrated safety interlock: automatic motor shutdown occurs if measured torque exceeds user-defined thresholds, preventing mechanical overload and preserving calibration integrity.
• Modular design supports field-upgradable configurations—including extended low-temperature capability and software-enabled data logging.

Sample Compatibility & Compliance

The instrument accommodates standard ASTM-compliant grease specimens in accordance with specimen preparation protocols outlined in Annex A1 of ASTM D1478 and Section 7 of ASTM D4693. Each test position accepts a single grease-filled bearing assembly (for D4693) or a grease-packed cup with rotating spindle (for D1478/D4950). All hardware—including spindles, bearing housings, and thermal probes—is traceably calibrated per ISO/IEC 17025-accredited procedures. The system’s temperature uniformity and stability across the working volume are validated against ASTM E74 and ISO 17025 requirements. Full compliance documentation—including factory calibration certificates, uncertainty budgets, and conformance statements for ASTM D1478, D4693, and D4950—is supplied with each unit.

Software & Data Management

The optional K18871 Data Acquisition Software Package provides synchronized acquisition of torque vs. time profiles at user-selectable intervals (down to 100 ms resolution). It generates compliant reports including graphical overlays of starting torque peaks, steady-state running torque plateaus, and time-to-rotation metrics—all annotated with timestamped metadata, operator ID, and environmental conditions. Export formats include CSV, PDF, and XML for integration into LIMS or enterprise QA/QC databases. The software adheres to FDA 21 CFR Part 11 requirements for electronic records and signatures, supporting audit trails, role-based access control, and electronic signature workflows where GLP/GMP environments mandate regulatory traceability.

Applications

• Formulation development and screening of low-temperature grease performance for OEM specifications (e.g., GM 6277M, Ford WSS-M2C949-A).
• Quality assurance testing of incoming raw materials and finished grease batches prior to release.
• Failure analysis of grease-related cold-start failures in rolling element bearings and constant-velocity joints.
• Supporting regulatory submissions requiring ASTM D1478/D4693 data for aviation, military, or automotive lubricant approvals (e.g., MIL-PRF-23827, SAE J310).
• Research into thixotropic recovery kinetics and shear-dependent yield behavior at cryogenic temperatures.

FAQ

What ASTM standards does this instrument support?
It fully supports ASTM D1478 (low-temperature torque of grease in cups), ASTM D4693 (low-temperature torque in tapered roller bearings), and ASTM D4950 (classification of chassis and wheel bearing greases).
Can the same unit perform both D1478 and D4693 tests?
Yes—hardware configuration is interchangeable via optional test fixtures (LM-67010–LM-67048 for D4693 internal influence; LM-11910–LM-11949 for external influence), and firmware supports both test modes.
Is temperature calibration traceable to NIST?
Yes—each unit ships with a NIST-traceable temperature calibration certificate covering the full operating range, verified using dual platinum resistance thermometers (PRTs) per ASTM E74.
What data output formats are supported by the K18871 software?
CSV for spreadsheet analysis, PDF for audit-ready reporting, and XML for automated ingestion into LIMS or ERP systems.
Does the instrument require external coolant or liquid nitrogen?
No—it employs a self-contained, air-cooled mechanical cascade refrigeration system requiring only standard electrical supply and ambient ventilation.