Relative pronouns - the usage of the relative pronoun "which"

Jinbei

Member
Japan/Japanese
Hello everyone!

The following sentence defines the backlash as (found in a patent application):

The backlash is clearance which a gear can be moved without moving a mating gear when two gears engage with each other.

Since it appears in a patent application, I assume the relative pronoun "which" is used correctly. I understand what "backlash" means, but I have encountered a problem when I have tried to divide the sentence into two complete sentences to make sure I have fully understood it. The first one is easy: The backlash is clearance.

Can someone please help me with the second sentence?

"A gear can be moved clearance without ...." sounds awkard... but I am not so sure.

I would appreciate your help!

Jinbei
 
  • bartonig

    Senior Member
    UK English
    Jinbei said:
    Hello everyone!

    The following sentence defines the backlash as (found in a patent application):

    The backlash is clearance which a gear can be moved without moving a mating gear when two gears engage with each other.

    Since it appears in a patent application, I assume the relative pronoun "which" is used correctly. I understand what "backlash" means, but I have encountered a problem when I have tried to divide the sentence into two complete sentences to make sure I have fully understood it. The first one is easy: The backlash is clearance.

    Can someone please help me with the second sentence?

    "A gear can be moved clearance without ...." sounds awkard... but I am not so sure.

    I would appreciate your help!

    Jinbei

    The backlash is clearance which a gear can be moved without moving a mating gear when two gears engage with each other.

    When two gears engage with each other there is a backlash. The backlash is the clearance by which one gear can be moved without moving the mating gear.

    Personally I would not use the word clearance. I would use amount.
     

    Jinbei

    Member
    Japan/Japanese
    Thanks a lot for your prompt response.

    The phrase "by which" has never occurred to me. I think "the backlash is the amount of clearance by which ..." may be more appropriate as you suggested.

    Thanks again for your help.
    Jinbei
     

    nycphotography

    Senior Member
    American English
    Technically, as suggested by Bartonig, the definition as given is flawed.

    Backlash is the "movement" that can result due to the "clearance (or slop or slack or [free]play)" between the teeth of the gears.

    I personally don't like the use of backlash in this context, as backlash is generally associated with a "violent reaction" to something. My first suspicion is that was a common misuse of the word that became accepted usage through repetition.

    Gear backlash doesn't react violently the way a political backlash does.

    I would generally prever a word like "slack" or "free play" in this context.

    However, to fix the language of the given definition:

    The backlash is the amount, due to the clearance when two gears engage with each other, which a gear can be moved without moving a mating gear.
     

    Kelly B

    Senior Member
    USA English
    I understand your reservations about word backlash given its other meanings, NYC, but it is the correct technical term.

    Backlash is the distance through which a gear can be moved without moving the mating gear.

    Edited: removed radial
     

    nycphotography

    Senior Member
    American English
    Kelly B said:
    I understand your reservations about word backlash given its other meanings, NYC, but it is the correct technical term.

    Backlash is the radial distance through which a gear can be moved without moving the mating gear.

    It may be A correct technical term, but it is by no means THE (implying exclusivity) correct ONE.

    Thus my preference for synonyms which lack the other competing meanings. Again, such as "slack" or "free play", which are ALSO correct technical terms in this context.

    Further, I would suggest that backlash itself is merely the ABILITY to move. Only the "amount of backlash" or the "measure of backlash" can be expressed in units.

    But don't forget that not all gears are linear, therefore, backlash is not necessarily limited to a radial unit of measure.

    Which leads me to restate/correct my defintion from above:

    The backlash is movement of a gear, due to clearance where two gears engage each other, without movement of a mating gear.
     

    Kelly B

    Senior Member
    USA English
    "Radial" was not correct. I've removed it. Otherwise, I disagree.

    Stated another way, backlash is the difference between the width of the tooth and the width of the space between the teeth of the mating gear, as measured at the pitch circle where the teeth are designed to meet. It may alternatively be measured as the angle through which the gear may be turned without engaging the mating gear.
    If the gears are never turned in reverse, then the backlash is irrelevant - it never comes into play, so to speak, because the meshed gear teeth remain in contact. However, it is still a measurable quantity. It remains the potential distance or angle through which one of the gears could move, were it turned in reverse.
     
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