19. May dam (lu) rung
a. Lu rung tu hanh
Hinh 5-8. So do cau tao lu rung co nguon dong luc rieng
1-Dong co; 2- Tay lai dieu khien; 3- Ghe ngoi dieu khien; 4- Khung may; 5- He thong giam chan;6- Banh lu (trong lan); 7- Truyen dong dai; 8- Dong co dan dong rung; 9- Khop chuyen huong; 10- Khop noi.
Lu rung duoc su dung rat pho bien de dam len nen mong va be mat cong trinh. So voi cac loai lu tinh, lu rung cho chieu sau anh huong dam lon hon han. Chung rat thich hop voi cac loai nen a cat, a set, cac loai vat lieu co tinh chat hat nhu da dam, soi, be tong asphalt.
Lu rung co loai banh tron nhan thuong duoc su dung de dam len be mat cong trinh hoac nen co tinh chat hat. Lu rung loai co vau (chan cuu) thuong duoc dung de dam cac nen dat a set voi chieu sau anh huong lon.
Hinh 5-9. So do truyen dong cua lu rung co nguon dong luc rieng
1-Dong co diezel; 2- Banh da; 3- Hop banh rang truyen dong; 4- Ly hop; 5,6- banh dai; 7- Truc lech tam; 8- Giam chan; 9- Trong lan; 10- o do; 11- Khung may.
Theo so do truyen dong, khi dong co 1 quay, no se truyen cong suat va mo men toi truc lech tam 7 lam truc nay quay thong qua hop banh rang chuyen huong 3, khop noi truc 4 va bo truyen dong dai 5,6.
Voi cac loai may lu hien dai, ben canh he thong truyen dong co khi truyen thong, ngay cang duoc su dung nhieu he thong truyen dong thuy luc. o Viet nam lu rung cua cac hang Bomag (Cong hoa lien bang Duc), Dynapac (Thuy dien), Sakai (Nhat) duoc su dung nhieu va rat ua chuong.
Lu rung thuong duoc cau tao tu hai phan chinh: phan dau keo va phan bo cong tac.
Phan dau keo thuong mang nguon dong luc chinh dung cho ca bo may di chuyen va bo may rung. Voi cac may lu co su dung he thong truyen dong thuy luc, dong co dat tren phan dau keo duoc dung de dan dong bom
thuy luc. Tu bom, dau cao ap se duoc dan toi lam quay cac dong co thuy luc cua bo may di chuyen va bo gay rung, dong thoi dan toi cac xy lanh cua co cau lai.
b. Dam ban rung dong
Trong cac loai may dam rung, dam ban duoc su dung kha pho bien. May dam ban rung dong duoc dung thich hop doi voi cac loai dat roi, co kich thuoc hat khac nhau va luc lien ket giua chung co gia tri nho nhu dat cat, a set, soi va da dam nho. Theo kha nang di chuyen, may dam ban rung dong co hai kieu: kieu tu hanh nho dong co di chuyen hoac nho luc cam dinh huong va kieu khong tu hanh (loai nay chi rung thuan tuy, muon di chuyen phai co nguoi hoac may loi di). Theo dac tinh cua luc rung dong co loai tac dong vo huong va loai tac dong co huong. Voi may dam rung vo huong, luc rung dong co huong thay doi nhung gia tri khong doi, nguoc lai may dam rung co huong thi huong cua luc rung dong khong doi nhung gia tri cua no thay doi. May dam rung co huong duoc su dung pho bien hon vi chat luong dam tot hon, lam viec em, co kha nang tu di chuyen trong qua trinh lam viec, tuy nhien ket cau phuc tap hon va tai trong tac dung len truc lon.
So do cau tao va nguyen ly lam viec:
So do nguyen ly cau tao may dam ban kieu rung thuan tuy duoc the hien o hinh 5-10. Nguyen ly lam viec cua dam ban rung kieu nay het suc don gian, thuong la truyen dong co khi cho mot de balang (vat quay lech tam) quay de tao ra luc rung dong.
Hinh 5-11. So do nguyen ly cau tao may dam rung tu hanh
a,b- Vi tri lam viec cua dam; c- So do truyen dong
1- Dong co; 2,7- Truyen dong dai; 3- Hop gay rung; 4- Dem cao su; 5- Ban dam; 6- Truc truyen dong; 8- Banh rang truyen dong; 9- Banh lech tam.
So do nguyen ly cau tao may dam ban rung kieu tu di chuyen nho luc cam dinh huong duoc gioi thieu tren hinh 5-11. Cau tao cua loai may nay chi khac loai may khong di chuyen o cho than may duoc lap ghep voi de ban dam bang khop quay ban le, do do duong noi tam cua truc mang qua vang co the nam song song hay khong song song so voi mat dat tuy theo yeu cau dam tai cho hay cho may dam di chuyen.
