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Installation Instructions 

MODEL 900CA 

For Vehicles With Air Brakes 

 

1.  Horns should be mounted on top of cab, tilted slightly 

downward for best sound projection. 

 
2.  If cab is equipped with roof trim panel, remove to install horns. 
 
3.  Drill ½” and 11/32” holes (using gasket for template) in position 

desired for horns. 

 
4.  Place Mounting Pad between base of horn and top of cab roof. 
 
5.  Assemble valve and curved tension washer to horn. Insert 5/16” 

bolt through front hole of base and tighten nut and lockwasher. 

 
6.  Connect tubing from air supply it inlet on manual lanyard valve. 
 
7.  Punch hole in trim panel for valve lanyard. Lace lanyard 

through panel. Replace panel, fasten lanyard to convenient trim 
screw. 

 

 

CAUTION: Check local noise abatement ordinances to avoid legal violations. 

 

Important – Use Pipe Compound on Pipe  

Threads to Assure Air Tight Connections 

 

All Hadley products carry a limited warranty for 12 months from date of purchase. We will repair or replace, 
at our option, any defects in material and workmanship during this period when product and proof of 
purchase is returned to our service department at the address below. 

 
 

 
 
 
 
 

 

 

 

 

 

 

     

www.hadley-products.com 

 
 

Form No. H12228 
Page 1 
Rev. 7/28/04  

HADLEY PRODUCTS 

Attn: Service Department 
2851 Prairie SW, Suite D 

Grandville, MI 49418 

 

Service Department Direct: 616-249-8462

Main: 616-530-1717 

Fax: 616-530-3283 

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