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newSchoolWorks.com › VoTechWorks › Building & Construction › Elevator Mechanic (pre-apprentice) › Traction Elevator Systems › Lesson 4
BLD-ELEV10-03 · Lesson 4 · 14 clock hours · lab

Guide Rails, Car Frame, Platform, and Counterweight Assembly

Objective. Students will measure rail alignment using a plumb bob and feeler gauges, identify car frame members and their functions, and correctly torque a fishplate bolt to specification on a training rail section.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed professional engineer or master tradesperson or by a certification or approval body. It is a study draft and may contain errors. Do not use it as instructions for work on a job site or on live equipment. Always follow your instructor, your supervising professional, and current official references and regulations.

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Guide Rails, Car Frame, Platform, and Counterweight Assembly

Guide rails, the car frame, the platform, and the counterweight are the structural backbone of a traction elevator. Understanding how these components fit together — and how to verify that fit — is a core competency for every elevator mechanic and apprentice.

Guide Rails

Guide rails are cold-drawn steel T-sections fastened to the hoistway walls with brackets. They serve two purposes: they keep the car and counterweight traveling in a precise vertical path, and they provide a gripping surface for the safeties if the governor trips. Rails come in standard weights per yard (for example, 8 lb/ft and 15 lb/ft sections are common), and the design load determines which weight is specified.

Rail sections are joined end-to-end with fishplates — flat steel splice bars bolted on both sides of the joint. Fishplate bolts must be torqued to the manufacturer's specification. Under-torqued joints allow rail movement and vibration; over-torqued bolts can crack the web or strip threads. Always use a calibrated torque wrench and record the actual value.

Rail alignment is critical. A rail that leans out of plumb causes the car frame to bind against the guides, creates uneven safety-jaw contact, and accelerates guide-shoe wear. Alignment is checked with a plumb bob dropped from a known reference point and a feeler gauge inserted between the bob line and the rail face. Any deviation beyond the manufacturer's tolerance must be corrected by adjusting bracket shimming before the system is placed in service.

Car Frame

The car frame (also called the sling) is a rigid steel structure that carries the car platform and transmits all loads to the hoist ropes and, when the safeties engage, to the guide rails. Its main members are:

Guide shoes or roller guides are bolted to the uprights at top and bottom of the frame. They keep the car aligned on the rails.

Roller Guide Shoes

Roller guide shoes replace older sliding guide shoes on most modern installations. Each shoe contains three wheels (rollers) — one for each face of the T-rail (front face and two sides) — mounted in a spring-loaded housing. The springs keep the rollers in contact with the rail through curves and minor misalignments.

When disassembling a roller guide shoe, note the orientation of every part before removal. Clean the housing, inspect roller bearings for roughness or flat spots, and reinstall components in reverse order. Torque all fasteners to specification. A loose guide-shoe mounting bolt is a serious hazard: it allows the car frame to shift on the rail and could impair safety operation.

Counterweight

The counterweight rides in its own set of guide rails in the hoistway. It is assembled from a counterweight frame (similar in concept to the car frame) loaded with filler weights (cast-iron or concrete blocks). Total counterweight mass is typically set at the car weight plus approximately 40–50 percent of rated capacity, balancing the system at partial load and minimizing motor demand. The counterweight also has guide shoes or roller guides and, on many modern installations, carries its own safety device.

Clearance Checks

Guide shoe-to-rail clearance (the gap between the guide shoe lip or roller and the rail) must fall within the manufacturer's tolerance. Too little clearance causes binding; too much allows the car to weave, accelerates wear, and can cause noise. Use a steel tape and spirit level on the training rig to verify the car is level before measuring clearances, then insert the correct feeler gauge blade. Record your measurement; compare it to the tolerance listed in the manufacturer's documentation.

Safety Rules for This Lab

Key terms10

FishplateA flat steel splice bar bolted to both sides of a rail joint to connect two rail sections end-to-end and transfer loads across the joint.
Car frame (sling)The rigid steel structure — comprising crosshead, uprights, and safety plank — that suspends the car platform and transmits loads to the hoist ropes and guide rails.
CrossheadThe top horizontal beam of the car frame, where the hoist rope hitch or overhead sheave connects to the frame.
Safety plank (bolster)The bottom horizontal beam of the car frame that supports the car platform, typically through isolator pads.
Isolator padA rubber or urethane mount placed between the safety plank and the car platform to absorb vibration and reduce noise transmission.
Roller guide shoeA spring-loaded guide device with three rollers that contact the three faces of the T-rail, keeping the car or counterweight aligned in the hoistway.
Plumb bobA weighted tool suspended on a line used to establish a true vertical reference for checking rail alignment in the hoistway.
Feeler gaugeA set of precision-ground metal blades of known thickness used to measure small gaps, such as the clearance between a guide shoe and the rail face or the deviation of a rail from plumb.
CounterweightThe assembly of a steel frame loaded with filler weights that balances the car in the hoistway, reducing the torque demand on the drive machine.
Torque wrenchA calibrated tool that applies and measures a specific rotational force (torque) to a fastener, ensuring it is neither under- nor over-tightened.

Worked examples4

1. A plumb bob line is hung from the top rail bracket reference point. At a point 10 feet below, you insert feeler gauges between the bob line and the rail face. The 0.030-inch blade passes freely; the 0.035-inch blade does not fit. The manufacturer's maximum allowable deviation for this rail is 0.025 inch per 10 feet. Is the rail within tolerance, and by how much does it deviate from the limit?
  1. Step 1 – Identify the measured deviation. The largest blade that passes freely is 0.030 inch, and the next size (0.035 inch) does not fit. Therefore the actual deviation is between 0.030 inch and 0.035 inch. For a conservative pass/fail evaluation, use the confirmed passing value: 0.030 inch.
  2. Step 2 – Compare to the tolerance limit. Tolerance = 0.025 inch. Measured deviation = 0.030 inch.
  3. Step 3 – Calculate how far the rail exceeds the limit. Excess = 0.030 − 0.025 = 0.005 inch.
  4. Step 4 – State the conclusion. The rail is OUT of tolerance by at least 0.005 inch and must be realigned by adjusting bracket shimming before the system is placed in service.
Answer: The rail deviation is at least 0.030 inch, which exceeds the 0.025-inch limit by 0.005 inch. The rail must be realigned.
2. A fishplate bolt specification calls for 75 ft-lb of torque. Your torque wrench scale reads in inch-pounds (in-lb). What value should you set on the wrench?
  1. Step 1 – Recall the conversion factor. 1 ft-lb = 12 in-lb.
  2. Step 2 – Multiply the specified torque by the conversion factor. 75 ft-lb × 12 in-lb/ft-lb = 900 in-lb.
  3. Step 3 – Set the torque wrench to 900 in-lb and apply to the fishplate bolt until the wrench clicks or signals, confirming the target torque has been reached.
Answer: Set the torque wrench to 900 in-lb to achieve the required 75 ft-lb.
3. You are checking the guide shoe-to-rail clearance on one side of the car frame at the top guide shoe. The manufacturer specifies a clearance of 0.050 inch ± 0.010 inch (acceptable range: 0.040 inch to 0.060 inch). Your feeler gauge shows 0.045 inch fits and 0.050 inch does not. Is the clearance acceptable?
  1. Step 1 – Identify the measured clearance range. The 0.045-inch blade fits freely; the 0.050-inch blade does not. The actual clearance is between 0.045 inch and 0.050 inch.
  2. Step 2 – Identify the acceptable range from the specification. Minimum: 0.040 inch; Maximum: 0.060 inch.
  3. Step 3 – Compare. The confirmed measurement of 0.045 inch falls within 0.040–0.060 inch.
  4. Step 4 – State the conclusion. The clearance is within the manufacturer's acceptable range. No adjustment is needed.
Answer: A clearance of approximately 0.045 inch is within the 0.040–0.060 inch acceptable range; the guide shoe clearance is acceptable.
4. Three fishplate bolts are torqued and recorded as 73 ft-lb, 76 ft-lb, and 74 ft-lb. The specification is 75 ft-lb ± 5 ft-lb (acceptable range: 70–80 ft-lb). Calculate whether each bolt is within tolerance and find the average torque applied.
  1. Step 1 – Check each bolt against the range of 70–80 ft-lb. Bolt 1: 73 ft-lb — within range. Bolt 2: 76 ft-lb — within range. Bolt 3: 74 ft-lb — within range. All three are acceptable.
  2. Step 2 – Calculate the average torque. Sum = 73 + 76 + 74 = 223 ft-lb.
  3. Step 3 – Divide by the number of bolts. Average = 223 ÷ 3 = 74.33 ft-lb.
  4. Step 4 – Confirm the average is also within the acceptable range. 74.33 ft-lb is within 70–80 ft-lb.
Answer: All three bolts are within the 70–80 ft-lb tolerance. The average torque is approximately 74.3 ft-lb.

The math in this lesson2

Learners convert a 75 ft-lb fishplate bolt torque spec to inch-pounds.
N-Q.1N-Q.3
Brush up in the math halls at newSchoolWorks.com:
In class: Lab station rotation: at Station 1 students identify car frame components (uprights, crosshead, safety plank, isolator pads) on a cutaway display model; at Station 2 they torque fishplate bolts on a bench-mounted rail section using a calibrated torque wrench and record values; at Station 3 they check a pre-misaligned rail with a plumb bob and feeler gauge and calculate deviation. · Guided practice: students use a steel tape and level to check car-to-rail clearance (guide shoe to rail) on the training rig, record measurements, and compare to manufacturer tolerance. · Group exercise: disassemble and reassemble a roller guide shoe, identify each part, clean the housing, and reinstall with correct fastener torque.
Materials: Training traction rig with guide rails, calibrated torque wrench set, feeler gauges, plumb bobs, steel tape measures, spirit level, roller guide shoe assembly, fishplate bolt specimens, NEIEP Traction module
Check: Instructor observes torque procedure and checks recorded values against specification; feeler gauge reading must be within ±0.005 inch of instructor measurement; pass requires all three station tasks completed correctly with no unsafe acts.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Traction Elevator Components and Systems
1. What is the primary purpose of guide rails in a traction elevator hoistway?
Traction Elevator Components and Systems
2. Which car frame member supports the car platform and typically has isolator pads mounted on top of it?
Tools, Equipment, and Measurement
3. A torque specification for a fishplate bolt is listed as 60 ft-lb. A technician's wrench is calibrated in inch-pounds. What is the correct wrench setting?
Measurement, Inspection, and Quality
4. When checking rail plumb with a plumb bob, a technician finds that the 0.040-inch feeler gauge blade passes between the bob line and the rail face, but the 0.045-inch blade does not. The manufacturer's maximum allowable deviation is 0.035 inch. What should the technician do?
Traction Elevator Components and Systems
5. What is the function of isolator pads in a car frame assembly?
Safety and Hazard Identification
6. Before beginning hands-on work on the training elevator rig, which safety procedure must every student complete according to accepted industry practice?
Traction Elevator Components and Systems
7. A roller guide shoe on a traction elevator car uses three rollers. Which surfaces of the T-rail do the three rollers contact?
Traction Elevator Components and Systems
8. A counterweight is typically balanced to equal the car weight plus what approximate percentage of the elevator's rated load capacity?
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