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Manual Reference
Midmark 411 (75L) Power Examination Table Service and Parts Manual, Part No. 004-0042-00 Rev. P; Midmark 411 (75L) Installation and Operation Manual, Part No. 003-0833-00. Confirm the complete model suffix and serial-prefix applicability before using this procedure.
Manufacturer Recommendation / AEM Status
Perform the scheduled-maintenance inspection semiannually. The service manual requires inspection for damage, hardware and decals; lubrication; control and actuator checks; accessory/interlock checks; and the complete operational test.
Qualified personnel should use the revision-specific service manual because the 75L family includes multiple model suffixes, serial-prefix breaks, programmable/non-programmable configurations, and early/later safety-interlock differences. Apply stricter regulatory or facility requirements where applicable; a different interval belongs under the facility's approved AEM program.
What This PM Procedure Covers
- Identity, configuration, history, upholstery, structure, hardware, labels, power cord, and controls
- OEM-specified pivot, slide, and actuator ball-screw lubrication
- Powered motion directions, timing, ranges, drift, and base limit switches
- Treatment-pan and revision-specific headlock interlocks
- Headrest, foot extension, stirrups, treatment pan, column, accessories, and receptacles
- Programmable functions when equipped, rated-load testing, electrical safety, and final restoration
Required Tools and Equipment
- Applicable Midmark operator and service manuals for the exact model suffix/serial prefix
- Stopwatch, tape measure, protractor/digital inclinometer, and inspection light
- 45 lb calibrated static test load and, when safely supported by facility policy, 325 lb distributed rated-load test setup
- Silicone-based lubricant and STP treatment oil or exact service-manual-approved equivalent
- Cleaning products compatible with Midmark upholstery and surfaces
- Electrical safety analyzer suitable for grounded medical equipment
Step-by-Step PM Procedure
1. Verify Identity and Manual Applicability
Action: Record asset tag, complete model number/suffix, serial number/prefix, voltage, department, programmable/non-programmable configuration, controls, and accessories. Cross-reference the nameplate to the correct Midmark manual. Apply the 411 (75L) limits below only when the manual confirms them for the unit; use exact OEM data for any differing 75LE configuration.
Expected outcome: The unit matches CMMS and the correct revision-specific manual and configuration are established before testing.
2. Review History and Prepare Safely
Action: Review drift, motion, noise, overheating, control, interlock, receptacle, and electrical-safety complaints and prior repairs. Remove the patient and clinical load, clear the complete motion envelope, unplug before inspection, and arrange controlled test loads with adequate personnel and handling equipment.
Expected outcome: The table is safely available for PM and known defects or repair-related testing requirements are identified.
3. Clean and Inspect Upholstery
Action: Clean with products compatible with the applicable manual. Inspect seat, back, headrest, foot/leg section, seams, attachment points, and hook-and-loop retainers for rips, tears, excessive wear, looseness, staining, or exposed substrate.
Expected outcome: Upholstery is clean, securely attached, and free of damage that could affect safe patient use or infection control.
4. Inspect Structure, Hardware, and Labels
Action: Inspect covers, frame, column, welds, pivots, mounting points, fasteners, hardware, power-entry area, and floor-contact surfaces for cracks, dents, looseness, missing parts, corrosion, or other damage. Verify all warning, instructional, load, model, and serial labels are present and legible.
Expected outcome: No visible condition compromises safety or performance; hardware is present and secure and required labels are readable.
5. Inspect Power Cord, Controls, and Connections
Action: Inspect the hospital-grade power cord, grounding pin, plug, strain relief, hand-control pendant, optional foot control, cords, connectors, membranes, pedals, and hanger for damage, pinching, contamination, loose fit, or unintended activation. Verify controls are kept clear of moving parts.
Expected outcome: Power and control components are intact, clean, correctly retained, and safe to energize.
6. Inspect and Lubricate Moving Components
Action: Qualified personnel shall inspect exposed pivots, moving parts, accessories, and actuator ball screws. Lubricate exposed pivots and treatment-pan slides with silicone-based lubricant. Extend each actuator as directed, wipe contamination from the ball-screw threads, apply STP treatment oil or the exact approved equivalent, cycle through travel twice, and remove excess lubricant.
Expected outcome: Required points are clean and correctly lubricated, movement is smooth, and lubricant does not contaminate upholstery, controls, or walking surfaces.
7. Verify Manual Accessories and Headrest
Action: Remove/reinstall the foot extension and verify it latches securely. Extend each stirrup and verify easy movement, acceptable wear, and locking in all three lateral positions. Extend/retract/remove/reinstall the irrigation/treatment pan and verify its slide locks. Operate all headrest joints/handles; using the service-manual geometry, confirm no headrest drift under a 45 lb static load. Do not exceed manual test forces.
Expected outcome: Accessories are complete, move smoothly, latch/lock securely, and the headrest supports 45 lb without movement.
8. Verify Hand and Foot Controls
Action: Connect the table to a grounded, correctly polarized outlet of the nameplate voltage. With no patient and the path clear, operate TABLE/BASE UP and DOWN, BACK UP and DOWN, TILT UP and DOWN, and FOOT UP and DOWN from the hand control. Repeat all functions with the optional foot control.
Expected outcome: Every installed control commands only the selected direction; motion stops on release and no switch sticks or activates unintentionally.
9. Verify Motion Speeds and Ranges
Action: For applicable 60 Hz 411 (75L) units, time full upward travel and measure range: base 12 ±1 seconds and 22-40 inches ±1 inch; back 10 ±1 seconds and 0-85 degrees; tilt 14 ±1 seconds and 0-30 degrees foot-up; foot 12 ±1 seconds and -90 to 0 degrees. Use revision-specific limits for other configurations.
Expected outcome: All four functions move steadily through the specified range within the applicable time, without binding, excessive squeal, or abnormal noise.
10. Verify Drift and Base Limit Switches
Action: Position each powered section away from an endpoint, release the control, and observe for unintended movement. Run the base to both endpoints only long enough to confirm the up/down limit switches stop the actuator before its mechanical limits; do not continue commanding a stalled function.
Expected outcome: No actuator drifts, and both base limit switches stop the actuator cleanly before freewheeling or mechanical damage can occur.
11. Verify Pan Safety Interlock
Action: Lower the foot section, extend the treatment pan until the pan safety switch releases, and command FOOT UP. On programmable units, observe the PAN OUT indication. Fully stow the pan until the switch clicks, then command FOOT UP again.
Expected outcome: FOOT UP is inhibited with the pan extended, the applicable PAN OUT warning operates, and foot-up motion returns only after the pan is fully stowed.
12. Verify Headlock Safety Interlock When Equipped
Action: Identify whether the exact revision has the early headlock limit switch. With the back in the manual-specified test range and the pan stowed, carefully deflect the headrest mounting bracket and command TABLE DOWN, BACK DOWN, and TILT UP. Verify the applicable programmable warning tone.
Expected outcome: On equipped early units, all three hazardous motions are inhibited while the headlock is deflected and the programmable warning sounds about every two seconds. Do not fail later units solely because the manual confirms they lack this switch.
13. Verify Programmable Functions When Equipped
Action: Record existing programmed positions. Using safe unloaded positions and the revision-specific operator manual, verify PROGRAM mode, all installed position buttons, HOME, indicators, warning tones, and STOP/interruption behavior. Restore the facility's original positions after testing and do not perform control-board calibration unless repair or OEM instructions require it.
Expected outcome: Stored-position and HOME movements operate as documented, can be stopped safely, show no stored diagnostic fault, and original settings are restored.
14. Inspect Column Stability and Accessories
Action: With power removed and the table at a safe height, check the column for excessive side-to-side play without entering pinch points. Inspect paper holder, procto/knee-rest positions, accessory rails, attachments, and all installed options for completeness, wear, secure engagement, and correct function.
Expected outcome: The column is stable and every installed accessory is complete, secure, and functional.
15. Verify Accessory Receptacles on 115 VAC Units
Action: Inspect receptacles for damage, contamination, looseness, or heat. Verify correct output with an appropriate receptacle tester or safe known load and confirm there is no intermittent operation. Do not overload the receptacle.
Expected outcome: Each installed receptacle is secure, correctly wired, and supplies stable power without heat or damage.
16. Perform the Rated-Load Operational Test
Action: When permitted by the exact manual and facility lifting policy, safely distribute approximately 325 lb on the seat section using secured test weights and adequate personnel/handling aids. Run TABLE/BASE UP to maximum and DOWN to minimum once. Observe motion, noise, and limit-switch operation, then remove the load safely. Do not improvise with personnel as test weight.
Expected outcome: The base lifts and lowers the rated test load without squeal, stall, or excessive noise, and both endpoint limit switches stop the actuator without continued humming.
17. Perform Electrical Safety Testing
Action: Perform protective-earth continuity and applicable equipment/enclosure leakage-current tests using the facility's adopted standard for grounded medical equipment. Exercise the power cord during earth testing and test accessory receptacles as applicable. Record the analyzer, standard, test configuration, limits, and readings; the cited OEM manuals do not publish numeric electrical-PM acceptance limits.
Expected outcome: All electrical-safety results pass the documented governing standard with stable protective-earth continuity and no cord intermittency.
18. Restore and Document
Action: Remove all test loads/tools, wipe away excess lubricant, reconnect and secure controls/accessories, restore programmed positions and normal configuration, and complete a final unloaded motion, stop, pan-interlock, and visual check. Document measured times/ranges, load/interlock checks, electrical results, corrective action, and disposition.
Expected outcome: The table is clean, fully assembled, correctly configured, and either returned to service with complete records or clearly removed from service.
Electrical Safety Testing
The 411 (75L) uses a hospital-grade grounding plug and three-conductor power cord. Perform protective-earth continuity and applicable equipment/enclosure leakage testing to the facility's current adopted standard. Test installed 115 VAC accessory receptacles where applicable. The cited operator/service manuals do not specify numeric electrical-PM limits, so record and apply the governing standard rather than inventing values.
Pass / Fail Criteria
Pass
- Identity and exact manual applicability are confirmed; structure, hardware, labels, upholstery, power cord, controls, and accessories pass inspection
- Required pivot, slide, and actuator lubrication is complete
- All powered motions and installed controls pass the applicable speed/range limits without drift or abnormal noise
- Base limit switches, pan interlock, and the revision-appropriate headlock interlock pass
- Headrest supports the 45 lb static check and stirrups/foot extension/pan lock securely
- Programmable functions and 115 VAC accessory receptacles pass when equipped
- The authorized 325 lb rated-load test and adopted electrical-safety tests pass
Remove From Service
- Structural damage, excessive column play, damaged upholstery, loose/missing hardware, illegible safety labels, damaged power/control parts, or unsafe accessory exists
- A powered section binds, drifts, moves unexpectedly, fails its range/time check, squeals excessively, stalls, or does not stop correctly
- Pan or applicable headlock interlock, base limit switch, control, programmable stop, accessory receptacle, or rated-load test fails
- Headrest does not hold 45 lb, or a stirrup, foot extension, pan, or accessory fails to lock
- Any electrical-safety test fails or the correct model/serial-specific procedure cannot be established
Copy/Paste CMMS Work Order Procedure
Follow the exact current Midmark manual for the complete model suffix and serial prefix. This field guide does not replace OEM training, service documentation, safe test-weight handling, or facility policy.