An Analysis of the Lever Escapement Trivia Quiz Questions and Answers

In 1910, what metric measurement was equal to 393708⁄10000 inches?

• Meter
• Millimeter
• Centimeter
• Kilometer

Correct Answer Explanation: This conversion factor was essential for understanding the metric system used in horology at the time.

What type of escapement was the lever escapement derived from?

• Anchor escapement
• Chronometer escapement
• Gravity escapement

Correct Answer Explanation: The lever escapement was derived from Graham’s dead-beat escapement for clocks.

What type of pallets are sometimes called “tangential escapement?”

• Circular pallets
• Equidistant pallets
• Club tooth pallets
• Ratchet pallets

Correct Answer Explanation: Equidistant pallets are sometimes called the tangential escapement because the unlocking takes place on the intersection of tangents to the primitive circle.

What type of tooth offers a constant lever length and less drop and lock?

• Club tooth
• Ratchet tooth
• Both club and ratchet teeth
• Neither club or ratchet teeth

Correct Answer Explanation: The ratchet wheel offers advantages over the club tooth wheel. It has a constant lever length, less drop and lock, and is better suited to a wide pallet.

What is the recommended total lock for the lever escapement?

• 1½°
• 1¾°

Correct Answer Explanation: A total lock of 1¾° is recommended for the lever escapement. This includes both the lock and the run.

Why is a larger roller required for a smaller impulse angle?

• To provide a more secure connection
• To allow for a greater drop angle
• To increase the lifting angle
• To place the ruby pin further from the center

Correct Answer: To place the ruby pin further from the center

Correct Answer Explanation: A larger roller is required for a smaller impulse angle because the ruby pin must be placed further from the center.

What is the recommended width of the ruby pin?

• Equal to the angular motion of the fork
• Half the angular motion of the fork
• Double the angular motion of the fork
• A quarter of the angular motion of the fork

Correct Answer: Half the angular motion of the fork

Correct Answer Explanation: A width of ruby pin equal to half the angular motion of the fork is recommended. This balances the needs of the unlocking and impulse actions.

What is the ideal proportion for the fork and impulse angles in a single roller escapement?

• 1:1
• 2:1
• 3:1
• 4:1

Correct Answer Explanation: A proportion of 3 to 1 for the fork and impulse angles is recommended for a single roller escapement. This balances the needs of the unlocking and impulse actions.

What is the recommended lifting angle for the lever escapement?

• 8½°
• 10°

Correct Answer Explanation: A lifting angle of 8½° is advisable for the lever escapement. This ensures a free vibration of the balance and an energetic movement.

How many teeth are typically found on an escape wheel in a lever escapement?

• 10
• 15
• 20
• 25

Correct Answer Explanation: While the number of teeth in the escape wheel is not fixed, 15 teeth are common in a lever escapement.

Why is a narrow pallet paired with a wide tooth more efficient than a wide pallet and a narrow tooth?

• It reduces frictional forces and improves lifting angle distribution
• It increases unlocking resistance and provides more power
• It reduces the drop angle and improves the lock action
• It allows for a larger center distance and better balance

Correct Answer: It reduces frictional forces and improves lifting angle distribution

Correct Answer Explanation: A narrow pallet paired with a wide tooth offers superior performance compared to a wide pallet and a narrow tooth. This is due to the lesser frictional forces involved and the more efficient distribution of the lifting angle.

What is the center distance of the wheel and pallets in relation to the direction of pressure of the wheel teeth?

• The pressure should be perpendicular to the pallet center
• The pressure should be parallel to the pallet center
• The pressure should be directed through the pallet center
• The pressure should be directed away from the pallet center

Correct Answer: The pressure should be directed through the pallet center

Correct Answer Explanation: The center distance of wheel and pallets should be such that the direction of pressure of the wheel teeth is through the pallet center. This is achieved by drawing tangents to the primitive circle.

What does a round ruby pin violate?

• The law of gravity
• The law of friction
• The law of the parallelogram of forces
• The law of momentum

Correct Answer: The law of the parallelogram of forces

Correct Answer Explanation: A round ruby pin should never be used because it violates the law of the parallelogram of forces and increases friction during unlocking and impulse.

What is the freedom between the guard point and the roller in a lever escapement?

• 1¼°
• 1½°

Correct Answer Explanation: The freedom between the guard point and the roller should be 1¼°. This ensures that the escapement remains locked even when the guard point is pressed against the roller.

Which type of escapement uses a crescent and two rollers?

• Double roller escapement
• Single roller escapement
• Savage pin roller escapement
• Tangential escapement

Correct Answer Explanation: A double roller escapement is preferable to a single roller escapement, as it provides greater safety and stability. By separating the impulse and safety actions, the escapement can function more reliably, especially in watches with finer proportions.

What is the radius of the safety roller in relation to the theoretical impulse radius?

• 1/3
• 2/5
• 4/7
• 5/8

Correct Answer Explanation: The radius of the safety roller should be 4/7 of the theoretical impulse radius. This proportion ensures a balance between the safety action and the impulse action.

What type of escapement combines the benefits of both wide and narrow ruby pins?

• Single roller escapement
• Double roller escapement
• Savage pin roller escapement
• Tangential escapement

Correct Answer: Savage pin roller escapement

Correct Answer Explanation: The Savage pin roller escapement is a unique variation on the lever escapement that combines the benefits of both wide and narrow ruby pins.

What is the acting length of the fork in a lever escapement?

• Equal to the center distance of the escape wheel and pallets
• Double the center distance of the escape wheel and pallets
• Half the center distance of the escape wheel and pallets
• A quarter of the center distance of the escape wheel and pallets

Correct Answer: Equal to the center distance of the escape wheel and pallets

Correct Answer Explanation: The acting length of the fork is equal to the center distance of the escape wheel and pallets. This ensures a fork of a fair length.

What is the recommended angle for the pallet in the Savage pin roller escapement?

• 10°
• 12°
• 15°
• 18°

Correct Answer Explanation: A 12° pallet angle and a proportion of 3 to 1 for the impulse and pallet angles are recommended for the Savage pin roller escapement. This ensures the delicate action of this escapement.

What is the recommended proportion for the impulse and pallet angles in the Savage pin roller escapement?

• 1:1
• 2:1
• 3:1
• 4:1

Correct Answer Explanation: A 12° pallet angle and a proportion of 3 to 1 for the impulse and pallet angles are recommended for the Savage pin roller escapement. This ensures the delicate action of this escapement.

Why is a larger drop angle wasteful?

• It increases the friction in the escapement
• It decreases the unlocking resistance
• It weakens the impulse action
• It wastes power and contributes to irregularity

Correct Answer: It wastes power and contributes to irregularity

Correct Answer Explanation: The drop should be as small as possible. Excessive drop wastes power and contributes to irregularity.

What is the angle of opening for the crescent in a double roller escapement?

• The same as in a single roller escapement
• Greater than in a single roller escapement
• Less than in a single roller escapement
• Not applicable

Correct Answer: Greater than in a single roller escapement

Correct Answer Explanation: The angle of opening for the crescent in the double roller escapement is greater than in the single roller escapement. This is because the safety roller is closer to the balance center.

What is the width of the slot in the fork of a lever escapement?

• 5⅛°

Correct Answer Explanation: The width of the slot in the fork is 5⅛°. This provides sufficient space for the ruby pin to move freely.

What is the ideal length of the horn in a double roller escapement?

• Equal to the diameter of the ruby pin
• Half the diameter of the ruby pin
• Twice the diameter of the ruby pin
• Such that the end points at least to the center of the ruby pin when the edge of the crescent passes the guard point

Correct Answer: Such that the end points at least to the center of the ruby pin when the edge of the crescent passes the guard point

Correct Answer Explanation: The length of the horn should be such that the end points at least to the center of the ruby pin when the edge of the crescent passes the guard point. This ensures the safety of the ruby pin.

Why is a deeper lock undesirable?

• It increases the unlocking resistance
• It reduces the lifting angle
• It decreases the drop angle
• It makes the escapement more sensitive to shock

Correct Answer: It increases the unlocking resistance

Correct Answer Explanation: The lock should be as small as possible. A deeper lock increases the unlocking resistance.

Why is a larger run undesirable?

• It decreases the lifting angle
• It increases the angular connection of the balance with the escapement
• It makes the escapement more sensitive to shock
• It reduces the drop angle

Correct Answer: It increases the angular connection of the balance with the escapement

Correct Answer Explanation: The run or slide should also be as small as possible. A larger run increases the angular connection of the balance with the escapement.

What is the space between the end of the horn and the ruby pin in a double roller escapement?

• ½°
• 1½°

Correct Answer Explanation: The space between the end of the horn and the ruby pin should be 1½°. This provides sufficient clearance to avoid collisions.

What is the purpose of the draw angle in a lever escapement?

• To increase the lifting angle
• To decrease the unlocking resistance
• To draw the fork back against the bankings
• To regulate the drop angle

Correct Answer: To draw the fork back against the bankings

Correct Answer Explanation: The draw angle is necessary to draw the fork back against the bankings. It is measured from the locking edges of the pallets.

What is the relationship between the pallet and tooth width?

• A narrow pallet requires a wide tooth
• A wide pallet requires a narrow tooth
• Both pallets require narrow teeth
• Both pallets require wide teeth

Correct Answer: A narrow pallet requires a wide tooth

Correct Answer Explanation: A narrow pallet requires a wide tooth, and a wide pallet requires a narrow or thin tooth wheel. The relationship between pallet and tooth width is crucial for efficient lifting.

What is the difference in the loss of lift between equidistant and circular pallets?

• The loss of lift is greater in the circular pallet
• The loss of lift is the same in both types of pallets
• The loss of lift is greater in the equidistant pallet
• There is no loss of lift in either type of pallet

Correct Answer: The loss of lift is greater in the equidistant pallet

Correct Answer Explanation: The loss of lift is greater in the equidistant pallet than in the circular pallet. This is due to the difference in the paths of the discharging edges and the deviation of the tangents from the circle.

What is the advantage of using circular pallets in general-purpose watches?

• They offer less unlocking resistance
• They offer a more favorable lifting action
• They are more resistant to shock
• They require less maintenance

Correct Answer: They offer a more favorable lifting action

Correct Answer Explanation: Circular pallets are better suited for general-purpose watches than equidistant pallets. While equidistant pallets offer less unlocking resistance, circular pallets offer a more favorable lifting action and are less prone to certain defects.

What is the relationship between the lifting angle on the tooth and its width?

• The lifting angle must be greater in proportion to its width
• The lifting angle must be the same as its width
• The lifting angle must be less in proportion to its width
• The lifting angle is not related to the width of the tooth

Correct Answer: The lifting angle must be less in proportion to its width

Correct Answer Explanation: The lifting angle on the tooth must be less in proportion to its width than it is on the pallet. This is essential for a smooth and efficient lifting action.

What is the lift composed of?

• The actual lift on the teeth and pallets
• The lock
• The run
• All of the above

Correct Answer: All of the above

Correct Answer Explanation: The lift is composed of the actual lift on the teeth and pallets, the lock, and the run. The smaller the lifting angle, the more energetic the movement.

What does the term “primitive diameter” refer to?

• The diameter of the escape wheel measured across the locking corners of the teeth
• The diameter of the balance wheel
• The diameter of the pallet arbor
• The diameter of the ruby pin

Correct Answer: The diameter of the escape wheel measured across the locking corners of the teeth

Correct Answer Explanation: The primitive diameter is the diameter of the escape wheel measured across the locking corners of the teeth.

What type of pallets offer less unlocking resistance?

• Circular pallets
• Equidistant pallets
• Club tooth pallets
• Ratchet pallets

Correct Answer Explanation: Equidistant pallets offer less unlocking resistance, but they are not as favorable for general purpose watches as circular pallets.

What is the advantage of a pallet embracing three teeth?

• It offers several geometrical and mechanical advantages
• It provides a more secure connection
• It increases the lifting angle
• It reduces the drop angle

Correct Answer Explanation: The pallet embracing three teeth is sound and practical. It offers several geometrical and mechanical advantages.

What is the key to optimizing the lever escapement?

• Balancing the conflicting needs of the unlocking and impulse actions
• Increasing the drop angle
• Decreasing the lifting angle
• Using a single roller escapement

Correct Answer: Balancing the conflicting needs of the unlocking and impulse actions

Correct Answer Explanation: Playtner emphasized the importance of balancing the conflicting needs of the unlocking and impulse actions to optimize overall performance.

When was the lever escapement adapted for use in watches?

• 1650
• 1750
• 1850
• 1950

Correct Answer Explanation: The lever escapement was adapted for use in watches around 1750.

Who was the first horologist to successfully apply the detached lever escapement to watches?

• John Harrison
• Thomas Mudge
• Abraham-Louis Breguet
• George Graham

Correct Answer Explanation: Thomas Mudge was the first horologist to successfully apply the detached lever escapement to watches. This innovation greatly improved the accuracy of watches.

What is the side shake for a balance pivot?

• .001 mm
• .01 mm
• .1 mm
• 1 mm

Correct Answer Explanation: The side shake for a balance pivot is .01 mm. This represents the amount of lateral movement allowed for the pivot.

What is the thickness for the spring detent of a pocket chronometer?

• About the thickness of a human hair
• About ⅓ the thickness of a human hair
• About 1/10 the thickness of a human hair
• About 1/100 the thickness of a human hair

Correct Answer Explanation: The thickness for the spring detent of a pocket chronometer is about ⅓ the thickness of a human hair. This illustrates the precision required in watchmaking.

Why is the lever escapement considered the best form of escapement for a general-purpose watch?

• It offers the highest accuracy
• It offers the most reliable performance
• It offers a good balance of accuracy and reliability
• It is the least expensive escapement to manufacture

Correct Answer: It offers a good balance of accuracy and reliability

Correct Answer Explanation: The lever escapement is the best form of escapement for a general-purpose watch. It offers a good balance of accuracy and reliability.