JP4137720B2

JP4137720B2 - Steering structure of four-wheel drive lawn mower

Info

Publication number: JP4137720B2
Application number: JP2003182994A
Authority: JP
Inventors: 勝彦上村; 博之小笠原; 宏樹永井
Original assignee: Kubota Corp
Current assignee: Kubota Corp
Priority date: 2003-06-26
Filing date: 2003-06-26
Publication date: 2008-08-20
Anticipated expiration: 2023-06-26
Also published as: JP2005014773A

Description

【０００１】
【発明の属する技術分野】
本発明は、４輪駆動型の芝刈り機に用いる操向構造に関する。
【０００２】
【従来の技術】
４輪駆動型の芝刈り機では、操向車輪である左右の前車輪をデフ機構を介して駆動するとともに、非操向車輪である後車輪をデフロック付きのデフ機構を介して駆動するのが一般的となっている（特許文献１参照）。また、デフ機構を介して駆動される左右の後車輪をサイドブレーキによって左右独立的に制動できるよう構成したものも利用されている（特許文献２参照）。
【０００３】
前後車輪を共にデフ機構を介して駆動する構造は、機体操向の程度に応じて内外輪に速度差がもたらされて、４輪駆動による確実な、かつ、滑らかな機体操向を行えるものであるが、機体の最少旋回半径がやゝ大きいものとなるものであり、狭い芝地や複雑な形状の芝地での芝刈り作業には難点がある。これに対して、左右後車輪にサイドブレーキを備えた構造のものでは、必要に応じて旋回内側となる後車輪に制動をかけることで小回り旋回が可能となり、狭い芝地や複雑な形状の芝地での芝刈り作業を難なく行える利点をもたらす。
【０００４】
しかしながら、サイドブレーキで旋回内側の後車輪を制動して小回り旋回すると、サイドブレーキによって固定された旋回内側の後車輪に引きずり移動が発生してて走行地面を荒らしやすくなり、芝刈り機の場合には芝を傷めてしまうことになる。
【０００５】
そこで、操向車輪である左右の前車輪をデフ機構を介して駆動するとともに、非操向輪である後車輪をそれぞれサイドクラッチを介して駆動するよう構成し、
前車輪が直進状態から設定角度以上に操向されると、旋回内側となる後車輪のサイドクラッチを自動的に切り作動させるようにステアリング機構とサイドクラッチとを機械的に連動したものも開発されている（特許文献３参照）。
【０００６】
この構成によると、旋回内側となる後車輪が遊転状態となるので、固定したままでの車輪の引きずりがなく、簡単容易に小回り旋回を行うことができるものでありながら走行地面を荒らしにくい特徴を有するものである。
【０００７】
【特許文献１】
特開２００３−１０６４１２号公報
【０００８】
【特許文献２】
特開２０００−５３０３２号公報
【０００９】
【特許文献３】
特開２００３−１７０８５９号公報
【００１０】
【発明が解決しようとする課題】
旋回内側となる後車輪のサイドクラッチを自動的に切り操作する上記操向構造は、ステアリングハンドルを回動操作するだけで３輪駆動による小回り旋回を簡単容易に実行することができるので、未熟な作業者でも容易に乗りこなせることができる実用上の利点が大きいものであるが、構造上で多少の難点があった。
【００１１】
つまり、従来構造では、前車輪（操向車輪）が設定角度以上に操向されると旋回内側のサイドクラッチを操作するクラッチレバーがクラッチ切り位置まで操作され、サイドクラッチが切り操作された後の更なる操向に対しては、クラッチ操作用のリンク機構に介在したストローク吸収用の圧縮コイルバネを弾性変形させて、クラッチレバーに必要以上に大きく操作しないようにしている。この場合、ストローク吸収用の前記バネは、サイドクラッチの入り付勢力に打ち勝ってクラッチレバー切り操作できるように予め圧縮変形されており、ストローク吸収作動はこの圧縮コイルバネを更に圧縮変形させることになる。従って、従来構造では、サイドクラッチが切られる領域までステアリング操作すると、その操作荷重が次第に大きくなるものとなっており、パワーステアリング装置を備えない仕様の機種では機体操向時のハンドル荷重が重く感じるものであった。
【００１２】
本発明はこのような点に着目してなされたものであって、サイドクラッチを自動的に切り作動させて軽快な小回り旋回を行うことができる利点を発揮させながら、この小回り旋回領域でのステアリングハンドル操作を軽快に行うことができるようにすることを目的としている。
【００１３】
【課題を解決するための手段】
【００１４】
第１の発明による４輪駆動型芝刈り機の操向構造は、機体前部の左右の操向車輪をデフ機構を介して駆動するとともに、機体後部の非操向車輪をそれぞれサイドクラッチを介して駆動するよう構成し、
前記操向車輪の操向作動と連動して変位作動する作動部材と、左右のサイドクラッチを選択的に切り操作するクラッチ操作部材とをカム機構を介して連係し、
前記操向車輪が直進姿勢から設定角度以上に操向されることに連動して前記クラッチ操作部材がカム機構を介して設定量だけ変位作動され、このクラッチ操作部材の前記設定量の変位作動によって、旋回内側となる非操向車輪のサイドクラッチが入り付勢力に抗して自動的に切り操作されるようにクラッチ操作部材とサイドクラッチとを機械的に連動連結し、
前記カム機構を、ステアリングハンドルの回動操作によって正逆に回動される作動部材に備えた接当部材と、前記クラッチ操作部材と一体変位するカム部材とで構成し、
前記カム部材に、直進姿勢で前記接当部材が位置する中立位置から、左方への操向時に前記接当部材によって接当操作される第１カム部と、前記中立位置から右方への操向時に前記接当部材によって接当操作される第２カム部とを備え、
前記第１カム部と第２カム部とのそれぞれは、前記作動部材に備えた接当部材の移動軌跡と同一の曲率の部分円弧面に形成してあるとともに、前記接当部材が中立位置に位置する直進姿勢では、前記第１カム部と第２カム部とが共に前記移動軌跡の曲率中心側へ入り込む姿勢となるように、互いのカム部同士の相対姿勢を設定してあり、
前記カム機構を、前記操向車輪が操向作動する縦軸芯位置よりも機体後方側に配設してあることを特徴とする。
【００１５】
上記構成によると、操向車輪を設定角度に達しない直進走行や緩やかな機体旋回時には左右のサイドクラッチは共に「クラッチ入り」状態に保持され、左右の非操向車輪は等速で駆動される。
そして、操向車輪が設定角度以上に操向されると、ステアリング機構の作動に連動してカム機構が機能し、クラッチ操作部材が設定角度だけ回動作動することで旋回内側となる一方の非操向車輪のサイドクラッチだけが自動的に切り操作され、操向された左右の操向車輪と旋回外側となる他方の非操向車輪の３輪駆動状態で機体は操向車輪の操向された方向に旋回してゆく。
【００１６】
この場合、操向車輪が設定角度以上に操向されたサイドクラッチ切り領域では、クラッチ操作部材はクラッチ切り操作に必要な設定量だけしか操作されないので操向するに連れて操作荷重が大きくなるようなことはない。
【００１７】
従って、第１の発明によると、地面や芝を傷めることの少ない小回り旋回を特別な運転技量を要することなく簡単容易に行うことができるとともに、操向するに連れて操向操作が重くなることもなく軽快に小回り旋回を行うことが可能となった。
【００１８】
第２の発明は、機体前部の左右の操向車輪をデフ機構を介して駆動するとともに、機体後部の非操向車輪をそれぞれサイドクラッチを介して駆動するよう構成し、
前記操向車輪の操向作動と連動して変位作動する作動部材と、左右のサイドクラッチを選択的に切り操作するクラッチ操作部材とをカム機構を介して連係し、
前記操向車輪が直進姿勢から設定角度以上に操向されることに連動して前記クラッチ操作部材がカム機構を介して設定量だけ変位作動され、このクラッチ操作部材の前記設定量の変位作動によって、旋回内側となる非操向車輪のサイドクラッチが入り付勢力に抗して自動的に切り操作されるようにクラッチ操作部材とサイドクラッチとを機械的に連動連結し、
前記カム機構を、ステアリングハンドルの回動操作によって正逆に回動される作動部材に備えた接当部材と、前記クラッチ操作部材と一体変位するカム部材とで構成し、
前記カム部材に、直進姿勢で前記接当部材が位置する中立位置から、左方への操向時に前記接当部材によって接当操作される第１カム部と、前記中立位置から右方への操向時に前記接当部材によって接当操作される第２カム部とを備え、
前記第１カム部と第２カム部とのそれぞれは、前記作動部材に備えた接当部材の移動軌跡と同一の曲率の部分円弧面に形成してあるとともに、前記接当部材が中立位置に位置する直進姿勢では、前記第１カム部と第２カム部とが共に前記移動軌跡の曲率中心側へ入り込む姿勢となるように、互いのカム部同士の相対姿勢を設定してあり、
前記カム部材を、左方への操向時に前記接当部材によって接当操作される第１カム部と、右方への操向時に前記接当部材によって接当操作される第２カム部とを備えた単一の部材で構成してあることを特徴とする。
【００１９】
上記構成によると、操向車輪が設定角度以上に操向されると、接当部材によってカム部材の一方のカム部が操作され、このカム部材と一体作動するクラッチ操作部材が設定角度だけ回動作動することで旋回内側となる一方の非操向車輪のサイドクラッチだけが自動的に切り操作され、操向された左右の操向車輪と旋回外側となる他方の非操向車輪の３輪駆動状態で機体は操向車輪の操向された方向に旋回してゆく。
【００２０】
従って、第２の発明によると、左右のクラッチ操作系に対してカム部材およびクラッチ操作部材が単一であるので、構成部品点数が少なく、構造の簡素化を図ることができるとともに、安価に実施できる。
【００２１】
第３の発明は、機体前部の左右の操向車輪をデフ機構を介して駆動するとともに、機体後部の非操向車輪をそれぞれサイドクラッチを介して駆動するよう構成し、
前記操向車輪の操向作動と連動して変位作動する作動部材と、左右のサイドクラッチを選択的に切り操作するクラッチ操作部材とをカム機構を介して連係し、
前記操向車輪が直進姿勢から設定角度以上に操向されることに連動して前記クラッチ操作部材がカム機構を介して設定量だけ変位作動され、このクラッチ操作部材の前記設定量の変位作動によって、旋回内側となる非操向車輪のサイドクラッチが入り付勢力に抗して自動的に切り操作されるようにクラッチ操作部材とサイドクラッチとを機械的に連動連結し、
前記カム機構を、ステアリングハンドルの回動操作によって正逆に回動されるステアリング操作部材に備えた接当部材と前記クラッチ操作部材と一体変位するカム部材とで構成し、
前記カム部材に、直進姿勢で前記接当部材が位置する中立位置から、左方への操向時に前記接当部材によって接当操作される第１カム部と、前記中立位置から右方への操向時に前記接当部材によって接当操作される第２カム部とを備え、
前記第１カム部と第２カム部とのそれぞれは、前記作動部材に備えた接当部材の移動軌跡と同一の曲率の部分円弧面に形成してあるとともに、前記接当部材が中立位置に位置する直進姿勢では、前記第１カム部と第２カム部とが共に前記移動軌跡の曲率中心側へ入り込む姿勢となるように、互いのカム部同士の相対姿勢を設定してあり、
左方への操向時に前記接当部材によって接当操作される第１カム部を備えたカム部材と、右方への操向時に前記接当部材によって接当操作される第２カム部を備えたカム部材を別体に構成するとともに、各カム部材と一体に変位作動するクラッチ操作部材を備えてあることを特徴とする。
【００２２】
上記構成によると、操向車輪が設定角度以上に操向されると、接当部材によって一方のカム部材だけが操作され、このカム部材と一体作動する一方のクラッチ操作部材が設定角度だけ回動作動することで旋回内側となる一方の非操向車輪のサイドクラッチだけが自動的に切り操作され、操向された左右の操向車輪と旋回外側となる他方の非操向車輪の３輪駆動状態で機体は操向車輪の操向された方向に旋回してゆく。この場合、他方のカム部材およびクラッチ操作部材は作動することがなく、直進操向時の「クラッチ入り」状態に保持される。
【００２３】
従って、第３の発明によると、左右のクラッチ操作系が独立するので、一方の系が操作される際に他方の操作系に影響を及ぼさないためのストローク吸収用の長孔などの融通手段が不要となり、長孔への異物の詰まり、などの融通手段での作動不良などが発生するおそれがなくなり、常に円滑な作動が期待できる。
【００２４】
【発明の実施の形態】
図１に、本発明に係る乗用型芝刈り機の全体側面図が示されている。この乗用型芝刈り機は、操向車輪としての前車輪１および非操向車輪としての後車輪２がそれぞれ駆動される４輪駆動型に構成された乗用型の走行車体３の下腹部に、前リンク４ａおよび後リンク４ｂからなる四連リンク機構４を介してモーア５が平行昇降操作可能に吊り下げ連結されるとともに、車体後部にモーア５で刈取った刈芝を集める集草容器６が連結された構造となっている。
【００２５】
走行車体３に備えられた左右一対の主フレーム７の前部には、左右に前車輪１を操向可能に装備した前車軸ケース８が前後軸心ａ周りにローリング可能に配備されるとともに、ボンネット９で覆われたエンジン１０が搭載され、また、主フレーム７の後部には、左右の後車輪２を装備したミッションケース１１が固着されている。また、主フレームの上部には、ステップ１２が搭載連結されるとともに、このステップ１２の後部に連設された左右フェンダ部１２ａの間に運転座席１３が配備されている。
【００２６】
図２に示すように、エンジン１０の出力が伝動軸１４を介してミッションケース１１の入力軸１５に伝達されて走行系と作業系に分岐され、その走行系動力は、ミッションケース１１の後端に連結配備された前後進切換え可能な油圧式無段変速装置（ＨＳＴ）１６に入力され、この無段変速装置１６の出力軸１６ａから取り出された正転（前進用）あるいは逆転（後進用）の変速動力が、ギヤ伝動機構１７を介してカウンター軸１８に伝達され、このカウンター軸１８が左右のサイドクラッチ１９および減速ギヤ２０，２１を介して左右の後車軸２２に連動連結されている。また、無段変速装置１６の出力軸１６ａから取り出された動力の一部は、ギヤ伝動機構２３を介して前車輪駆動軸２４にも分岐伝達され、この前車輪駆動軸２４からミッションケース前方に取り出された動力が、車体下腹部に沿って前方に延出配備された伝動軸２５ａ，２５ｂを介して前車軸ケース８の内装デフ機構３０に伝達され、前車輪１が後車輪２とが同調した速度で駆動されるようになっている。また、ミッションケース内で分岐された作業系の動力は、ＰＴＯクラッチ２６を介してミッションケース前面のＰＴＯ軸２７から取り出され、伝動軸２８を介してモーア５に伝達されるようになっている。
【００２７】
なお、図３，図５に示すように、前記ミッションケース１１の主部は走行車体３に対して左横側方に偏って配備されており、その偏在によって空けられた車体下方空間に、モーア５から放出された刈芝を集草容器６に導くダクト２９が配備されている。
【００２８】
図４に示すように、前記サイドクラッチ１９は、カウンター軸１８にシフト可能にスプライン装着されたクラッチ部材３１、カウンター軸１８に遊嵌支持された減速ギヤ２０と一体化したクラッチドラム３２、クラッチ部材３１とクラッチドラム３２に係合されて交互に積層された多数のクラッチディスク群３３、クラッチ部材３１を図４において左方向にスライド付勢してクラッチディスク群３３を圧接するバネ３４、等を備えた多板式クラッチに構成されている。
【００２９】
このサイドクラッチ１９は、通常は、クラッチ部材３１をバネ３４でシフトしてクラッチディスク群３３を圧接することで、クラッチ部３１材からクラッチドラム３２へ動力を伝達し、ミッションケース１１に軸支装着したシフトフォーク３５を図４において時計回り方向に回動操作して、クラッチ部材３１をバネ３４に抗して図４において右方にシフトさせることでクラッチディスク群３３の圧接を解除してクラッチ部３１材からクラッチドラム３２への動力伝達を断つように構成されている。
【００３０】
前記シフトフォーク３５の支軸３６がミッションケース１１の後面に突設されて、その突出端部にクラッチレバー３７が連結されている。左右のクラッチレバー３７は前車輪１の操向操作に連動して自動的に操作されるようになっており、以下、その操向構造について説明する。
【００３１】
図５に示すように、前車軸ケース８の左右両端部に縦軸心ｂ周りに回動可能に装着された回動ケース４１に前車輪１が軸支装着されており、左右の回動ケース４１の上端に連結されたナックルアーム４２が互いにタイロッド４３で連結されるとともに、一方（この例では左側）のナックルアーム４２が縦支点ｃを中心に回動可能なピットマンアーム４５にドラックリンク４４を介して連動連結されている。ピットマンアーム４５は、前車輪１の操向作動と連動して変位作動する作動部材としてのセクトギヤ４６から一体に延出されており、セクトギヤ４６に咬合させたピニオンギヤ４７を運転座席前方のステアリングハンドル４８によって回動操作することでピットマンアーム４５を回動させて前車輪１を操向するステアリング機構が構成されている。
【００３２】
図７，図８に示すように、前記ピットマンアーム４５およびセクトギヤ４６は、左右の主フレーム７に亘って架設されたステー５０にボス５１を介して縦支点ｃ周りに回動自在に軸支されており、このセクトギヤ４６と左右の前記サイドクラッチ１９とがカム機構５２を介してワイヤ連係されている。
【００３３】
前記カム機構５２は、ステー５０の上面にブラケット５３を介して縦軸心ｄを中心に回動可能に軸支されたカム部材５４と、ボス５５を介してカム部材５４に一体化されたクラッチ操作部材５６と、カム部材５４に作用する接当部材としてセクトギヤ４６に装着したローラ５７とから構成されており、クラッチ操作部材５６に一端を連結した２本のレリーズワイヤ５８の他端が前記サイドクラッチ１９の各クラッチレバー３７にそれぞれ連結されている。
【００３４】
図９に示すように、前記カム部材５４には、ローラ５７に向けて先拡がり姿勢に対向する第１カム部５９ａと第２カム部５９ｂとが形成されており、セクトギヤ４６が直進位置にある時には、ローラ５７が第１カム部５９ａと第２カム部５９ｂとの間の中立凹部６０に落ち込んだ状態で安定保持され、図１０に示すように、セクトギヤ４６が図中反時計回りに回動されて前車輪１が直進位置から右方に操向されると、ローラ５７が第２カム部５９ｂを押圧してカム部材５４が図中時計回りに回動され、これと一体回動するクラッチ操作部材５６の同方向への回動に伴って一方のレリーズワイヤ５８が引き操作されて、旋回内側となる右側の後車輪２に対するクラッチレバー３７だけがクラッチ切り方向に操作されるようになっている。
【００３５】
また、図示しないが、セクトギヤ４６が図中時計回りに回動されて前車輪１が直進位置から左方に操向されると、ローラ５７が第１カム部５９ａを押圧してカム部材５４が図中反時計回りに回動され、これと一体回動するクラッチ操作部材５６の同方向への回動に伴って他方のレリーズワイヤ５８が引き操作されて、旋回内側となる左側の後車輪２に対するクラッチレバー３７だけがクラッチ切り方向に操作されるようになっている。
【００３６】
ここで、前記第１カム部５９ａおよび第２カム部５９ｂは、セクトギヤ４６が回動する際にローラ５７が縦支点ｃ周りに回動移動する際のローラ外周端の移動軌跡Ｓと同一の曲率の部分円弧面に形成されており、例えば、図６，図１０に示すように、操向ローラ５７が中立凹部６０を超えて移動して第２カム部５９ｂを押圧した右方操向状態では、押圧移動された第２カム部５９ｂがローラ５７の外周端移動軌跡Ｓと一致した状態となり、引き続く同方向への操向操作によってローラ５７が同方向に移動してもカム部材５４は変位作動しないようになっている。
【００３７】
つまり、セクトギヤ４６が所定角度以上に回動されて前車輪１が直進位置から所定角度（例えば、２０°）以上に操向操作されると、旋回内側となる後車輪２に対するクラッチレバー３７がクラッチ切りに必要な量だけ回動操作されて、それ以降の同方向への操向操作に対してはクラッチレバー３７がそれ以上にクラッチ切り方向に回動操作されないものとなっている。
【００３８】
なお、各レリーズワイヤ５８のアウター前端部は、前記ブラケット５３に連設されたワイヤ受け部５３ａに支持されるとともに、インナー前端に取付けた前端金具６１がクラッチ操作部材５６に長孔６２と連結ピン６３を介して連結され、かつ、クラッチ入り状態における前端金具６１はブラケット５３に連設された接当部５３ｂの前面に受け止められ、クラッチ操作部材５６が回動されて一方のレリーズワイヤ５８がクラッチ切り方向に引き操作された際に、引き操作されない他方のレリーズワイヤ５８の連結ピン６３が長孔６２内で確実に移動してストローク吸収作動するように構成されている。
【００３９】
また、図４に示すように、クラッチレバー３７の延長部には、このクラッチレバー３７をクラッチ入り（ＯＮ）側に向けて軽く回動付勢するワイヤ弛み取り用のバネ６４が装着されて、クラッチ入り作動を確実なものにしている。
【００４０】
〔別実施形態〕
本発明は、以下のような形態で実施することもできる。
【００４１】
（１）図１１に示すように、左右のクラッチレバー３７にワイヤ連係したクラッチ操作部材５６およびカム部材５４を左右独立したものに構成して実施することもできる。これによると、クラッチ操作部材５６とレリーズワイ５８とを、先例のように、長孔融通をもって連結する必要はなくなる。
【００４２】
（２）上記実施例は、クラッチ操作部材５６とクラッチレバー３７とをワイヤ連係した場合を例示したが、レリーズワイヤ５８に代えてロッドを利用することもできる。
【００４３】
（３）上記実施例では、前車輪１の操向作動と連動して変位作動する作動部材の一例であるセクトギヤ４６にローラ（接当部材）５７を備えてカム部材５４を接当押圧変位させるようにカム機構５２を構成しているが、カム部材５４をセクトギヤ４６（あるいはピットマンアーム４５）に備えるとともに、クラッチ操作部材５６にローラ（接当部材）５７を備えて実施することも可能である。
【００４４】
（４）ラック・ピニオンを利用して直線的に変位作動する作動部材で前車輪１を操向するステアリング機構を利用するものにおいては、前記ローラ（接当部材）の直線移動をカム機構５２を介してクラッチ操作部材５６の設定量の変位作動（回動変位あるいは直線変位）に変換するように構成することも可能である。
【００４５】
【００４６】
【図面の簡単な説明】
【図１】乗用芝刈り機の全体側面図
【図２】ミッションケースの概略構成を示す側面図
【図３】後部伝動部の正面図
【図４】ミッションケース主部と左側サイドクラッチを示す正面図
【図５】操向構造の直進状態を示す平面図
【図６】操向構造の右方操向状態を示す平面図
【図７】操向操作部とカム機構を示す平面図
【図８】操向操作部とカム機構を示す背面図
【図９】直進状態におけるカム機構を示す展開平面図
【図１０】右方操向状態におけるカム機構を示す展開平面図
【図１１】別実施例のカム機構を示す平面図
【符号の説明】
１操向車輪（前車輪）
２非操向車輪（議車輪）
１９サイドクラッチ
３０デフ機構
４６作動部材（セクトギヤ）
４８ステアリングハンドル
５２カム機構
５４カム部材
５６クラッチ操作部材
５７接当部材（ローラ）
５９ａ第１カム部
５９ｂ第２カム部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering structure used for a four-wheel drive type lawn mower.
[0002]
[Prior art]
In a four-wheel drive lawn mower, the left and right front wheels, which are steered wheels, are driven through a differential mechanism, and the rear wheels, which are non-steered wheels, are driven through a differential mechanism with a differential lock. It is common (see Patent Document 1). Further, a configuration in which left and right rear wheels driven via a differential mechanism can be braked independently by left and right sides by a side brake is also used (see Patent Document 2).
[0003]
The structure in which both the front and rear wheels are driven through the differential mechanism is a mechanism that provides a speed difference between the inner and outer wheels in accordance with the degree of steering, enabling reliable and smooth steering by four-wheel drive. However, the minimum turning radius of the fuselage is slightly larger, and there is a difficulty in mowing the lawn on narrow turf and complex turf. On the other hand, in the structure with side brakes on the left and right rear wheels, it is possible to make a small turn by applying braking to the rear wheels on the inside of the turn if necessary, so that a narrow grass or a complex-shaped turf is possible. This provides the advantage that the mowing work on the ground can be done without difficulty.
[0004]
However, if the rear wheel inside the turn is braked with the side brake and the small turn is made, dragging will occur on the rear wheel inside the turn fixed by the side brake, which will easily roughen the running ground. Will hurt the lawn.
[0005]
Therefore, the left and right front wheels, which are steered wheels, are driven via a differential mechanism, and the rear wheels, which are non-steer wheels, are each driven via a side clutch,
When the front wheels are steered beyond the set angle from the straight traveling state, a mechanical linkage between the steering mechanism and the side clutch has been developed so that the side clutch of the rear wheel on the inside of the turn is automatically turned off. (See Patent Document 3).
[0006]
According to this configuration, since the rear wheels on the inside of the turn are in a free-wheeling state, there is no drag of the wheels while they are fixed, and it is possible to easily make a small turn, but it is difficult to rough the running ground It is what has.
[0007]
[Patent Document 1]
JP 2003-106412 A
[Patent Document 2]
Japanese Patent Laid-Open No. 2000-53032
[Patent Document 3]
Japanese Patent Laid-Open No. 2003-170859
[Problems to be solved by the invention]
The steering structure that automatically turns the side clutch of the rear wheel on the inside of the turn can easily perform a small turn by three-wheel drive by simply turning the steering handle. Although there are great practical advantages that an operator can easily get on, there are some structural difficulties.
[0011]
In other words, in the conventional structure, when the front wheel (steering wheel) is steered beyond the set angle, the clutch lever that operates the side clutch on the inside of the turn is operated to the clutch disengagement position, and after the side clutch is disengaged. For further steering, the stroke absorbing compression coil spring interposed in the clutch operating link mechanism is elastically deformed so that the clutch lever is not operated more than necessary. In this case, the stroke absorbing spring is compressed and deformed in advance so that the clutch lever can be operated by overcoming the urging force of the side clutch, and the stroke absorbing operation further compresses and deforms the compression coil spring. Therefore, in the conventional structure, when the steering operation is performed to the area where the side clutch is disengaged, the operation load gradually increases, and in the model without the power steering device, the steering wheel load during steering is felt heavy. It was a thing.
[0012]
The present invention has been made paying attention to such points, and it is possible to steer in this small turning region while demonstrating the advantage that the side clutch can be automatically turned off to perform a light small turning. The purpose is to enable easy operation of the steering wheel.
[0013]
[Means for Solving the Problems]
[0014]
The steering structure of the four-wheel drive lawn mower according to the first aspect of the invention drives the left and right steering wheels at the front of the fuselage via a differential mechanism, and the non-steering wheels at the rear of the fuselage via side clutches, respectively. Configured to drive
An operation member that is displaced in conjunction with the steering operation of the steering wheel and a clutch operation member that selectively disengages the left and right side clutches are linked via a cam mechanism,
The clutch operating member is displaced by a set amount via a cam mechanism in conjunction with the steering wheel being steered from a straight traveling posture by a set angle or more, and by the displacement operation of the set amount of the clutch operating member. The clutch operating member and the side clutch are mechanically interlocked and connected so that the side clutch of the non-steering wheel on the inside of the turn is automatically turned off against the urging force,
The cam mechanism is composed of a contact member provided in an operation member that is rotated forward and backward by a rotation operation of a steering handle, and a cam member that is integrally displaced with the clutch operation member,
A first cam portion that is contacted by the contact member when the steering member is steered to the left from a neutral position where the contact member is positioned in a rectilinear posture on the cam member, and a rightward direction from the neutral position. A second cam portion that is contacted by the contact member during steering,
Wherein a first cam part each of the second cam portion, together with some form on partial arc surface of the same curvature and the movement trajectories of the contact member with the actuating member, said abutment member is a neutral position In the straight-ahead posture positioned at the position, the relative postures of the cam portions are set so that both the first cam portion and the second cam portion are in the posture of entering the center of curvature of the movement locus,
The cam mechanism is arranged on the rear side of the machine body from the vertical axis position where the steering wheel steers.
[0015]
According to the above configuration, both the left and right side clutches are kept in the “clutch-engaged” state when the steering wheel does not reach the set angle and the vehicle is turning slowly, and the left and right non-steering wheels are driven at a constant speed. .
When the steered wheel is steered beyond the set angle, the cam mechanism functions in conjunction with the operation of the steering mechanism, and the clutch operating member rotates only the set angle so that one of the non-turns is turned inside. Only the side clutch of the steered wheel is automatically turned off, and the aircraft is steered by the steered wheel in the three-wheel drive state of the steered left and right steered wheels and the other non-steered wheel outside the turning. It turns in the direction.
[0016]
In this case, in the side clutch disengagement region where the steered wheel is steered beyond the set angle, the clutch operating member is operated only by the set amount necessary for the clutch disengagement operation, so that the operation load increases as the operation is performed. There is nothing wrong.
[0017]
Therefore, according to the first aspect of the invention, it is possible to easily and easily perform a small turn without damaging the ground or the lawn without requiring a special driving skill, and the steering operation becomes heavier as the steering is performed. It became possible to make a small turn without any difficulty.
[0018]
The second invention is configured to drive the left and right steered wheels at the front of the aircraft via a differential mechanism and to drive the non-steered wheels at the rear of the aircraft via side clutches,
An operation member that is displaced in conjunction with the steering operation of the steering wheel and a clutch operation member that selectively disengages the left and right side clutches are linked via a cam mechanism,
The clutch operating member is displaced by a set amount via a cam mechanism in conjunction with the steering wheel being steered from a straight traveling posture by a set angle or more, and by the displacement operation of the set amount of the clutch operating member. The clutch operating member and the side clutch are mechanically interlocked and connected so that the side clutch of the non-steering wheel on the inside of the turn is automatically turned off against the urging force,
The cam mechanism is composed of a contact member provided in an operation member that is rotated forward and backward by a rotation operation of a steering handle, and a cam member that is integrally displaced with the clutch operation member,
A first cam portion that is contacted by the contact member when the steering member is steered to the left from a neutral position where the contact member is positioned in a rectilinear posture on the cam member, and a rightward direction from the neutral position. A second cam portion that is contacted by the contact member during steering,
Each of the first cam portion and the second cam portion is formed on a partial arc surface having the same curvature as the movement locus of the contact member provided in the operating member, and the contact member is in the neutral position. In the rectilinear posture that is positioned, the relative postures of the cam portions are set so that both the first cam portion and the second cam portion are in a posture that enters the curvature center side of the movement locus,
A first cam portion that is operated to contact the cam member by the contact member when steering leftward; and a second cam portion that is operated to be contacted by the contact member when steering rightward. It is comprised by the single member provided with.
[0019]
According to the above configuration, when the steering wheel is steered beyond the set angle, one of the cam portions of the cam member is operated by the contact member, and the clutch operating member that operates integrally with the cam member rotates by the set angle. Only the side clutch of one non-steering wheel that is on the inside of the turn by moving is automatically disengaged, and the three-wheel drive of the left and right steered wheels that are steered and the other non-steering wheel that is on the outside of the turn In this state, the aircraft turns in the direction of the steering wheel.
[0020]
Therefore, according to the second invention, since the cam member and the clutch operation member are single with respect to the left and right clutch operation systems, the number of components can be reduced, the structure can be simplified, and the cost can be reduced. it can.
[0021]
The third invention is configured to drive the left and right steered wheels at the front of the aircraft via the differential mechanism and to drive the non-steered wheels at the rear of the aircraft via the side clutches,
An operation member that is displaced in conjunction with the steering operation of the steering wheel and a clutch operation member that selectively disengages the left and right side clutches are linked via a cam mechanism,
The clutch operating member is displaced by a set amount via a cam mechanism in conjunction with the steering wheel being steered from a straight traveling posture by a set angle or more, and by the displacement operation of the set amount of the clutch operating member. The clutch operating member and the side clutch are mechanically interlocked and connected so that the side clutch of the non-steering wheel on the inside of the turn is automatically turned off against the urging force,
The cam mechanism is composed of a contact member provided in a steering operation member that is rotated forward and backward by a rotation operation of a steering handle, and a cam member that is integrally displaced with the clutch operation member ,
A first cam portion that is contacted by the contact member when the steering member is steered to the left from a neutral position where the contact member is positioned in a rectilinear posture on the cam member, and a rightward direction from the neutral position. A second cam portion that is contacted by the contact member during steering,
Each of the first cam portion and the second cam portion is formed on a partial arc surface having the same curvature as the movement locus of the contact member provided in the operating member, and the contact member is in the neutral position. In the rectilinear posture that is positioned, the relative postures of the cam portions are set so that both the first cam portion and the second cam portion are in a posture that enters the curvature center side of the movement locus,
A cam member having a first cam portion that is contacted by the contact member when steering to the left, and a second cam portion that is contacted by the contact member when steering to the right The provided cam member is configured as a separate body, and a clutch operating member that is displaced in an integrated manner with each cam member is provided.
[0022]
According to the above configuration, when the steering wheel is steered beyond the set angle, only one cam member is operated by the contact member, and one clutch operating member that operates integrally with the cam member rotates only by the set angle. Only the side clutch of one non-steering wheel that is on the inside of the turn by moving is automatically disengaged, and the three-wheel drive of the left and right steered wheels that are steered and the other non-steering wheel that is on the outside of the turn In this state, the aircraft turns in the direction of the steering wheel. In this case, the other cam member and the clutch operating member are not actuated, and are maintained in the “clutch engaged” state during the straight traveling operation.
[0023]
Therefore, according to the third invention, the left and right clutch operating systems are independent, so that when one system is operated, there is an interchange means such as a stroke absorbing long hole so as not to affect the other operating system. This eliminates the need for a malfunction due to the accommodation means such as clogging of foreign matter into the long hole, and smooth operation can always be expected.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an overall side view of a riding lawn mower according to the present invention. This riding-type lawn mower is provided on the lower abdomen of a riding-type traveling vehicle body 3 configured as a four-wheel drive type in which a front wheel 1 as a steering wheel and a rear wheel 2 as a non-steering wheel are respectively driven. A mower 5 is suspended and connected through a four-link mechanism 4 composed of a front link 4a and a rear link 4b so as to be able to move up and down in parallel, and a grass collecting container 6 for collecting grass cut by the mower 5 at the rear of the vehicle body. It has a connected structure.
[0025]
At the front part of the pair of left and right main frames 7 provided in the traveling vehicle body 3, a front axle case 8 equipped with the front wheels 1 to be steerable to the left and right is arranged so as to be able to roll around the front and rear axis a, An engine 10 covered with a bonnet 9 is mounted, and a mission case 11 equipped with left and right rear wheels 2 is fixed to the rear portion of the main frame 7. In addition, a step 12 is mounted and connected to the upper part of the main frame, and a driver seat 13 is disposed between the left and right fender portions 12a connected to the rear portion of the step 12.
[0026]
As shown in FIG. 2, the output of the engine 10 is transmitted to the input shaft 15 of the transmission case 11 via the transmission shaft 14 and is branched into the traveling system and the working system. Forward rotation (for forward movement) or reverse rotation (for backward movement) taken out from an output shaft 16a of the continuously variable transmission 16 that is input to a continuously variable hydraulic continuously variable transmission (HST) 16 connected to Is transmitted to the countershaft 18 via the gear transmission mechanism 17, and this countershaft 18 is linked to the left and right rear axles 22 via the left and right side clutches 19 and the reduction gears 20 and 21. A part of the power extracted from the output shaft 16a of the continuously variable transmission 16 is also branched and transmitted to the front wheel drive shaft 24 via the gear transmission mechanism 23, and forward from the front wheel drive shaft 24 to the front of the transmission case. The extracted power is transmitted to the interior differential mechanism 30 of the front axle case 8 via transmission shafts 25a and 25b extending forward along the lower body of the vehicle body, and the front wheel 1 and the rear wheel 2 are synchronized. It is designed to be driven at a specified speed. The power of the work system branched in the transmission case is taken out from the PTO shaft 27 on the front surface of the transmission case via the PTO clutch 26 and transmitted to the mower 5 via the transmission shaft 28.
[0027]
As shown in FIGS. 3 and 5, the main portion of the transmission case 11 is arranged to be deviated to the left lateral side with respect to the traveling vehicle body 3, and the mower is located in the space below the vehicle body vacated by the uneven distribution. A duct 29 for guiding the cut grass discharged from 5 to the grass collection container 6 is provided.
[0028]
As shown in FIG. 4, the side clutch 19 includes a clutch member 31 that is spline-mounted on a counter shaft 18, a clutch drum 32 that is integrated with a reduction gear 20 that is loosely supported on the counter shaft 18, and a clutch member. 31 and a plurality of clutch disk groups 33 that are alternately stacked by engaging with the clutch drum 32, and a spring 34 that slidably biases the clutch member 31 leftward in FIG. It is composed of a multi-plate clutch.
[0029]
Normally, the side clutch 19 shifts the clutch member 31 with a spring 34 and presses the clutch disk group 33 so that power is transmitted from the material of the clutch portion 31 to the clutch drum 32, and is attached to the transmission case 11. 4 is rotated clockwise in FIG. 4, and the clutch member 31 is shifted to the right in FIG. 4 against the spring 34, so that the pressure contact of the clutch disk group 33 is released, and the clutch portion The power transmission from the 31 material to the clutch drum 32 is cut off.
[0030]
A support shaft 36 of the shift fork 35 protrudes from the rear surface of the transmission case 11, and a clutch lever 37 is connected to the protruding end portion. The left and right clutch levers 37 are automatically operated in conjunction with the steering operation of the front wheel 1, and the steering structure will be described below.
[0031]
As shown in FIG. 5, the front wheel 1 is pivotally mounted on a rotating case 41 that is rotatably mounted around the longitudinal axis b at the left and right ends of the front axle case 8, A knuckle arm 42 connected to the upper end of 41 is connected to each other by a tie rod 43, and one (the left side in this example) knuckle arm 42 has a drag link 44 attached to a pitman arm 45 that can rotate around a longitudinal fulcrum c. It is linked and connected through. The pitman arm 45 is integrally extended from a sect gear 46 as an operating member that is displaced in conjunction with the steering operation of the front wheel 1. A pinion gear 47 engaged with the sect gear 46 is a steering handle 48 in front of the driver's seat. The steering mechanism is configured to rotate the pitman arm 45 and to steer the front wheel 1 by performing a rotation operation.
[0032]
As shown in FIGS. 7 and 8, the pitman arm 45 and the sect gear 46 are pivotally supported around a longitudinal fulcrum c via a boss 51 on a stay 50 laid over the left and right main frames 7. The sect gear 46 and the left and right side clutches 19 are wire-coupled via a cam mechanism 52.
[0033]
The cam mechanism 52 includes a cam member 54 pivotally supported on the upper surface of the stay 50 via a bracket 53 so as to be rotatable about a longitudinal axis d, and a clutch integrated with the cam member 54 via a boss 55. An operation member 56 and a roller 57 attached to the sect gear 46 as a contact member acting on the cam member 54 are configured. The other end of two release wires 58 having one end connected to the clutch operation member 56 is the side member. Each clutch lever 37 of the clutch 19 is connected to each other.
[0034]
As shown in FIG. 9, the cam member 54 is formed with a first cam portion 59a and a second cam portion 59b that are opposed to a roller 57 in a pre-expanded posture, and the sect gear 46 is in a straight traveling position. Sometimes, the roller 57 is stably held in a state where it falls into the neutral recess 60 between the first cam portion 59a and the second cam portion 59b, and as shown in FIG. 10, the sect gear 46 rotates counterclockwise in the drawing. When the front wheel 1 is steered rightward from the rectilinear position, the roller 57 presses the second cam portion 59b and the cam member 54 is rotated clockwise in the figure, and the clutch rotates integrally therewith. As the operating member 56 rotates in the same direction, one release wire 58 is pulled, and only the clutch lever 37 for the right rear wheel 2 on the inside of the turn is operated in the clutch disengagement direction. Yes.
[0035]
Although not shown, when the sect gear 46 is rotated clockwise in the drawing and the front wheel 1 is steered to the left from the straight traveling position, the roller 57 presses the first cam portion 59a and the cam member 54 is moved. As the clutch operating member 56 that rotates counterclockwise in the figure rotates in the same direction as the clutch operating member 56 rotates in the same direction, the other release wire 58 is pulled, and the rear wheel 2 on the left side that is inside the turn. Only the clutch lever 37 is operated in the clutch disengagement direction.
[0036]
Here, the first cam portion 59a and the second cam portion 59b have the same curvature as the movement trajectory S of the outer peripheral edge of the roller 57 when the roller 57 rotates around the vertical fulcrum c when the sect gear 46 rotates. For example, as shown in FIGS. 6 and 10, in the right steering state where the steering roller 57 moves beyond the neutral recess 60 and presses the second cam portion 59b, as shown in FIGS. The cam member 54 is displaced even when the second cam portion 59b that has been pressed and moved coincides with the outer peripheral end movement locus S of the roller 57 and the roller 57 moves in the same direction by the subsequent steering operation in the same direction. It is supposed not to.
[0037]
That is, when the sect gear 46 is rotated by a predetermined angle or more and the front wheel 1 is steered by a predetermined angle (for example, 20 °) or more from the straight traveling position, the clutch lever 37 for the rear wheel 2 on the inside of the turn is clutched. The clutch lever 37 is not rotated further in the clutch disengagement direction for the steering operation in the same direction after that.
[0038]
The outer front end portion of each release wire 58 is supported by a wire receiving portion 53a connected to the bracket 53, and a front end fitting 61 attached to the inner front end is connected to the clutch operating member 56 with a long hole 62 and a connecting pin. 63, and the front end fitting 61 in the clutch-engaged state is received by the front surface of the contact portion 53b connected to the bracket 53, and the clutch operating member 56 is rotated so that one release wire 58 is connected to the clutch. When the pulling operation is performed in the cutting direction, the connecting pin 63 of the other release wire 58 that is not pulled is surely moved in the long hole 62 to perform a stroke absorbing operation.
[0039]
Further, as shown in FIG. 4, an extension portion of the clutch lever 37 is equipped with a wire slack removing spring 64 that lightly turns and biases the clutch lever 37 toward the clutch ON (ON) side, Ensuring clutch operation is ensured.
[0040]
[Another embodiment]
The present invention can also be implemented in the following forms.
[0041]
(1) As shown in FIG. 11, the left and right clutch operating members 56 and cam members 54 linked to the left and right clutch levers 37 may be configured independently. According to this, it is not necessary to connect the clutch operating member 56 and the release Y 58 with the long hole interchange as in the previous example.
[0042]
(2) In the above embodiment, the case where the clutch operating member 56 and the clutch lever 37 are linked by wire is illustrated, but a rod may be used instead of the release wire 58.
[0043]
(3) In the above embodiment, the sect gear 46, which is an example of an operating member that is displaced in conjunction with the steering operation of the front wheel 1, is provided with a roller (contacting member) 57 and the cam member 54 is pressed and displaced. Although the cam mechanism 52 is configured as described above, the cam member 54 may be provided in the sect gear 46 (or the pitman arm 45), and the clutch operating member 56 may be provided with a roller (contact member) 57. .
[0044]
(4) In the case of using a steering mechanism that steers the front wheel 1 with an operating member that linearly moves by using a rack and pinion, the cam mechanism 52 is used for linear movement of the roller (contacting member). It is also possible to convert the clutch operation member 56 into a displacement operation (rotation displacement or linear displacement) of a set amount.
[0045]
[0046]
[Brief description of the drawings]
[Fig. 1] Overall side view of a riding lawn mower [Fig. 2] Side view showing a schematic configuration of a transmission case [Fig. 3] Front view of a rear transmission [Fig. 4] Front showing a transmission case main part and a left side clutch FIG. 5 is a plan view showing the steering structure in a straight traveling state. FIG. 6 is a plan view showing the steering structure in the right direction. FIG. 7 is a plan view showing the steering operation section and the cam mechanism. FIG. 9 is a developed plan view showing the cam mechanism in the straight traveling state. FIG. 10 is a developed plan view showing the cam mechanism in the right steering state. FIG. Plan view showing the cam mechanism
1 Steering wheel (front wheel)
2 Non-steering wheels (conference wheels)
19 Side clutch 30 Differential mechanism 46 Actuating member (sect gear)
48 Steering handle 52 Cam mechanism 54 Cam member 56 Clutch operating member 57 Contact member (roller)
59a First cam portion 59b Second cam portion

Claims

The left and right steered wheels at the front of the fuselage are driven via a differential mechanism, and the non-steered wheels at the rear of the fuselage are each driven via a side clutch,
An operation member that is displaced in conjunction with the steering operation of the steering wheel and a clutch operation member that selectively disengages the left and right side clutches are linked via a cam mechanism,
The clutch operating member is displaced by a set amount via a cam mechanism in conjunction with the steering wheel being steered beyond a set angle from a straight running posture, and by the displacement operation of the set amount of the clutch operating member The clutch operating member and the side clutch are mechanically interlocked and connected so that the side clutch of the non-steering wheel on the inside of the turn is automatically turned off against the urging force,
The cam mechanism is composed of a contact member provided in an operation member that is rotated forward and backward by a rotation operation of a steering handle, and a cam member that is integrally displaced with the clutch operation member,
A first cam portion that is abutted by the abutting member when steered to the left from a neutral position where the abutting member is positioned in a rectilinear posture on the cam member, and a rightward direction from the neutral position. A second cam portion that is contacted by the contact member during steering,
Each of the first cam portion and the second cam portion is formed on a partial arc surface having the same curvature as the movement locus of the contact member provided in the operating member, and the contact member is in the neutral position. In the rectilinear posture that is positioned, the relative postures of the cam portions are set so that both the first cam portion and the second cam portion are in a posture that enters the curvature center side of the movement locus,
A steering structure for a four-wheel drive type lawn mower, characterized in that the cam mechanism is disposed on the rear side of the machine body relative to a vertical axis position where the steering wheel steers.

The left and right steered wheels at the front of the fuselage are driven via a differential mechanism, and the non-steered wheels at the rear of the fuselage are each driven via a side clutch,
An operation member that is displaced in conjunction with the steering operation of the steering wheel and a clutch operation member that selectively disengages the left and right side clutches are linked via a cam mechanism,
The clutch operating member is displaced by a set amount via a cam mechanism in conjunction with the steering wheel being steered beyond a set angle from a straight running posture, and by the displacement operation of the set amount of the clutch operating member The clutch operating member and the side clutch are mechanically interlocked and connected so that the side clutch of the non-steering wheel on the inside of the turn is automatically turned off against the urging force,
The cam mechanism is composed of a contact member provided in an operation member that is rotated forward and backward by a rotation operation of a steering handle, and a cam member that is integrally displaced with the clutch operation member,
A first cam portion that is contacted by the contact member when the steering member is steered to the left from a neutral position where the contact member is positioned in a rectilinear posture on the cam member, and a rightward direction from the neutral position. A second cam portion that is contacted by the contact member during steering,
Each of the first cam portion and the second cam portion is formed on a partial arc surface having the same curvature as the movement locus of the contact member provided in the operating member, and the contact member is in the neutral position. In the rectilinear posture that is positioned, the relative postures of the cam portions are set so that both the first cam portion and the second cam portion are in a posture that enters the curvature center side of the movement locus,
A first cam portion that is operated to contact the cam member by the contact member when steering leftward; and a second cam portion that is operated to be contacted by the contact member when steering rightward. A steering structure for a four-wheel drive type lawn mower characterized by comprising a single member comprising

The left and right steered wheels at the front of the fuselage are driven via a differential mechanism, and the non-steered wheels at the rear of the fuselage are each driven via a side clutch,
An operation member that is displaced in conjunction with the steering operation of the steering wheel and a clutch operation member that selectively disengages the left and right side clutches are linked via a cam mechanism,
The clutch operating member is displaced by a set amount via a cam mechanism in conjunction with the steering wheel being steered beyond a set angle from a straight running posture, and by the displacement operation of the set amount of the clutch operating member The clutch operating member and the side clutch are mechanically interlocked and connected so that the side clutch of the non-steering wheel on the inside of the turn is automatically turned off against the urging force,
The cam mechanism is composed of a contact member provided in a steering operation member that is rotated forward and backward by a rotation operation of a steering handle, and a cam member that is integrally displaced with the clutch operation member,
A first cam portion that is contacted by the contact member when the steering member is steered to the left from a neutral position where the contact member is positioned in a rectilinear posture on the cam member, and a rightward direction from the neutral position. A second cam portion that is contacted by the contact member during steering,
Each of the first cam portion and the second cam portion is formed on a partial arc surface having the same curvature as the movement locus of the contact member provided in the operating member, and the contact member is in the neutral position. In the rectilinear posture that is positioned, the relative postures of the cam portions are set so that both the first cam portion and the second cam portion are in a posture that enters the curvature center side of the movement locus,
A cam member having a first cam portion that is contacted by the contact member when steering to the left, and a second cam portion that is contacted by the contact member when steering to the right A steering structure for a four-wheel drive type lawn mower, wherein the cam member is provided separately, and a clutch operating member that is displaced in unison with each cam member is provided.